less: somewhat buggy applet, but nice. Muchly reduced

xstrdup'ing and memory consumption. Made linewrap saner.
regex matching code was awful - still buggy, but not as
leaky as before. Made buffer size configurable. Killed
several static and on-stack buffers. Hopefully eliminated
staircase effect on Ctrl-C (unable to reproduce).

2 files changed, 206 insertions, 212 deletions

diff --git a/miscutils/Config.in b/miscutils/Config.in
index 90e2b6fb1..01d1fa0a5 100644
--- a/miscutils/Config.in
+++ b/miscutils/Config.in
@@ -133,6 +133,11 @@ config LESS
           'less' is a pager, meaning that it displays text files. It possesses
           a wide array of features, and is an improvement over 'more'.
 
+config FEATURE_LESS_MAXLINES
+        int "Max number of input lines less will try to eat"
+        default 9999999
+        depends on LESS
+
 config FEATURE_LESS_BRACKETS
         bool "Enable bracket searching"
         default y
diff --git a/miscutils/less.c b/miscutils/less.c
index 03ffd78ed..73500671d 100644
--- a/miscutils/less.c
+++ b/miscutils/less.c
@@ -32,7 +32,7 @@
 
 #include "busybox.h"
 
-#ifdef CONFIG_FEATURE_LESS_REGEXP
+#if ENABLE_FEATURE_LESS_REGEXP
 #include "xregex.h"
 #endif
 
@@ -64,13 +64,12 @@
 /* The escape code to clear the screen */
 #define CLEAR "\033[H\033[J"
 
-/* Maximum number of lines in a file */
-#define MAXLINES 10000
+#define MAXLINES CONFIG_FEATURE_LESS_MAXLINES
 
 static int height;
 static int width;
 static char **files;
-static char filename[256];
+static char *filename;
 static char **buffer;
 static char **flines;
 static int current_file = 1;
@@ -79,24 +78,21 @@ static int num_flines;
 static int num_files = 1;
 
 /* Command line options */
-static unsigned flags;
 #define FLAG_E 1
 #define FLAG_M (1<<1)
 #define FLAG_m (1<<2)
 #define FLAG_N (1<<3)
 #define FLAG_TILDE (1<<4)
 /* hijack command line options variable for internal state vars */
-#define LESS_STATE_INP_STDIN (1<<5)
-#define LESS_STATE_PAST_EOF  (1<<6)
-#define LESS_STATE_MATCH_BACKWARDS (1<<7)
-/* INP_STDIN is used to change behaviour when input comes from stdin */
+#define LESS_STATE_PAST_EOF  (1<<5)
+#define LESS_STATE_MATCH_BACKWARDS (1<<6)
 
-#ifdef CONFIG_FEATURE_LESS_MARKS
+#if ENABLE_FEATURE_LESS_MARKS
 static int mark_lines[15][2];
 static int num_marks;
 #endif
 
-#ifdef CONFIG_FEATURE_LESS_REGEXP
+#if ENABLE_FEATURE_LESS_REGEXP
 static int match_found;
 static int *match_lines;
 static int match_pos;
@@ -143,7 +139,7 @@ static int tless_getch(void)
            them accordingly */
 
         if (input == '\033' && getc(inp) == '[') {
-                unsigned int i;
+                unsigned i;
                 input = getc(inp);
                 set_tty_cooked();
 
@@ -152,13 +148,12 @@ static int tless_getch(void)
                         return 20 + i;
                 else if ((i = input - REAL_PAGE_UP) < 4)
                         return 24 + i;
+                else
+                        return 0; /* ?? */
         }
         /* The input is a normal ASCII value */
-        else {
-                set_tty_cooked();
-                return input;
-        }
-        return 0;
+        set_tty_cooked();
+        return input;
 }
 
 /* Move the cursor to a position (x,y), where (0,0) is the
@@ -174,51 +169,62 @@ static void clear_line(void)
         printf("\033[K");
 }
 
-/* This adds line numbers to every line, as the -N flag necessitates */
-static void add_linenumbers(void)
-{
-        int i;
-
-        for (i = 0; i <= num_flines; i++) {
-                char *new = xasprintf("%5d %s", i + 1, flines[i]);
-                free(flines[i]);
-                flines[i] = new;
-        }
-}
-
 static void data_readlines(void)
 {
-        int i;
-        char current_line[256];
+        unsigned i;
+        unsigned n = 1;
+        int w = width;
+        char *last_nl = (char*)1; /* "not NULL" */
+        char *current_line;
         FILE *fp;
 
-        fp = (flags & LESS_STATE_INP_STDIN) ? stdin : xfopen(filename, "r");
+        fp = filename ? xfopen(filename, "r") : stdin;
         flines = NULL;
-        for (i = 0; (feof(fp)==0) && (i <= MAXLINES); i++) {
-                strcpy(current_line, "");
-                fgets(current_line, 256, fp);
+        if (option_mask32 & FLAG_N) {
+                w -= 6;
+                if (w < 1) w = 1; /* paranoia */
+        }
+        for (i = 0; !feof(fp) && i <= MAXLINES; i++) {
+                flines = xrealloc(flines, (i+1) * sizeof(char *));
+
+                current_line = xmalloc(w);
+ again:
+                current_line[0] = '\0';
+                fgets(current_line, w, fp);
                 if (fp != stdin)
                         die_if_ferror(fp, filename);
-                flines = xrealloc(flines, (i+1) * sizeof(char *));
-                flines[i] = xstrdup(current_line);
+
+                /* Corner case: linewrap with only '\n' wrapping */
+                /* Looks ugly on screen, so we handle it specially */
+                if (!last_nl && current_line[0] == '\n') {
+                        last_nl = (char*)1; /* "not NULL" */
+                        n++;
+                        goto again;
+                }
+                last_nl = last_char_is(current_line, '\n');
+                if (last_nl)
+                        *last_nl = '\0';
+                if (option_mask32 & FLAG_N) {
+                        flines[i] = xasprintf((n <= 99999) ? "%5u %s" : "%05u %s",
+                                                n % 100000, current_line);
+                        free(current_line);
+                        if (last_nl)
+                                n++;
+                } else {
+                        flines[i] = xrealloc(current_line, strlen(current_line)+1);
+                }
         }
         num_flines = i - 2;
 
         /* Reset variables for a new file */
 
         line_pos = 0;
-        flags &= ~LESS_STATE_PAST_EOF;
+        option_mask32 &= ~LESS_STATE_PAST_EOF;
 
         fclose(fp);
-
-        if (inp == NULL)
-                inp = (flags & LESS_STATE_INP_STDIN) ? xfopen(CURRENT_TTY, "r") : stdin;
-
-        if (flags & FLAG_N)
-                add_linenumbers();
 }
 
-#ifdef CONFIG_FEATURE_LESS_FLAGS
+#if ENABLE_FEATURE_LESS_FLAGS
 
 /* Interestingly, writing calc_percent as a function and not a prototype saves around 32 bytes
  * on my build. */
@@ -232,19 +238,18 @@ static void m_status_print(void)
 {
         int percentage;
 
-        if (!(flags & LESS_STATE_PAST_EOF)) {
+        if (!(option_mask32 & LESS_STATE_PAST_EOF)) {
                 if (!line_pos) {
-                        if (num_files > 1)
+                        if (num_files > 1) {
                                 printf("%s%s %s%i%s%i%s%i-%i/%i ", HIGHLIGHT,
                                         filename, "(file ", current_file, " of ", num_files, ") lines ",
                                         line_pos + 1, line_pos + height - 1, num_flines + 1);
-                        else {
+                        } else {
                                 printf("%s%s lines %i-%i/%i ", HIGHLIGHT,
                                         filename, line_pos + 1, line_pos + height - 1,
                                         num_flines + 1);
                         }
-                }
-                else {
+                } else {
                         printf("%s %s lines %i-%i/%i ", HIGHLIGHT, filename,
                                 line_pos + 1, line_pos + height - 1, num_flines + 1);
                 }
@@ -253,13 +258,11 @@ static void m_status_print(void)
                         printf("(END) %s", NORMAL);
                         if ((num_files > 1) && (current_file != num_files))
                                 printf("%s- Next: %s%s", HIGHLIGHT, files[current_file], NORMAL);
-                }
-                else {
+                } else {
                         percentage = calc_percent();
                         printf("%i%% %s", percentage, NORMAL);
                 }
-        }
-        else {
+        } else {
                 printf("%s%s lines %i-%i/%i (END) ", HIGHLIGHT, filename,
                                 line_pos + 1, num_flines + 1, num_flines + 1);
                 if ((num_files > 1) && (current_file != num_files))
@@ -287,10 +290,10 @@ static void medium_status_print(void)
 static void status_print(void)
 {
         /* Change the status if flags have been set */
-#ifdef CONFIG_FEATURE_LESS_FLAGS
-        if (flags & FLAG_M)
+#if ENABLE_FEATURE_LESS_FLAGS
+        if (option_mask32 & FLAG_M)
                 m_status_print();
-        else if (flags & FLAG_m)
+        else if (option_mask32 & FLAG_m)
                 medium_status_print();
         /* No flags set */
         else {
@@ -300,16 +303,14 @@ static void status_print(void)
                         if (num_files > 1)
                                 printf("%s%s%i%s%i%s%s", HIGHLIGHT, "(file ",
                                         current_file, " of ", num_files, ")", NORMAL);
-                }
-                else if (line_pos == num_flines - height + 2) {
+                } else if (line_pos == num_flines - height + 2) {
                         printf("%s%s %s", HIGHLIGHT, "(END)", NORMAL);
                         if ((num_files > 1) && (current_file != num_files))
                                 printf("%s%s%s%s", HIGHLIGHT, "- Next: ", files[current_file], NORMAL);
-                }
-                else {
+                } else {
                         putchar(':');
                 }
-#ifdef CONFIG_FEATURE_LESS_FLAGS
+#if ENABLE_FEATURE_LESS_FLAGS
         }
 #endif
 }
@@ -322,13 +323,12 @@ static void buffer_print(void)
         printf("%s", CLEAR);
         if (num_flines >= height - 2) {
                 for (i = 0; i < height - 1; i++)
-                        printf("%s", buffer[i]);
-        }
-        else {
+                        printf("%.*s\n", width, buffer[i]);
+        } else {
                 for (i = 1; i < (height - 1 - num_flines); i++)
                         putchar('\n');
                 for (i = 0; i < height - 1; i++)
-                        printf("%s", buffer[i]);
+                        printf("%.*s\n", width, buffer[i]);
         }
 
         status_print();
@@ -341,21 +341,18 @@ static void buffer_init(void)
 
         if (buffer == NULL) {
                 /* malloc the number of lines needed for the buffer */
-                buffer = xrealloc(buffer, height * sizeof(char *));
-        } else {
-                for (i = 0; i < (height - 1); i++)
-                        free(buffer[i]);
+                buffer = xmalloc(height * sizeof(char *));
         }
 
         /* Fill the buffer until the end of the file or the
            end of the buffer is reached */
         for (i = 0; (i < (height - 1)) && (i <= num_flines); i++) {
-                buffer[i] = xstrdup(flines[i]);
+                buffer[i] = flines[i];
         }
 
         /* If the buffer still isn't full, fill it with blank lines */
         for (; i < (height - 1); i++) {
-                buffer[i] = xstrdup("");
+                buffer[i] = "";
         }
 }
 
@@ -364,28 +361,25 @@ static void buffer_down(int nlines)
 {
         int i;
 
-        if (!(flags & LESS_STATE_PAST_EOF)) {
+        if (!(option_mask32 & LESS_STATE_PAST_EOF)) {
                 if (line_pos + (height - 3) + nlines < num_flines) {
                         line_pos += nlines;
                         for (i = 0; i < (height - 1); i++) {
-                                free(buffer[i]);
-                                buffer[i] = xstrdup(flines[line_pos + i]);
+                                buffer[i] = flines[line_pos + i];
                         }
-                }
-                else {
+                } else {
                         /* As the number of lines requested was too large, we just move
                         to the end of the file */
                         while (line_pos + (height - 3) + 1 < num_flines) {
                                 line_pos += 1;
                                 for (i = 0; i < (height - 1); i++) {
-                                        free(buffer[i]);
-                                        buffer[i] = xstrdup(flines[line_pos + i]);
+                                        buffer[i] = flines[line_pos + i];
                                 }
                         }
                 }
 
                 /* We exit if the -E flag has been set */
-                if ((flags & FLAG_E) && (line_pos + (height - 2) == num_flines))
+                if ((option_mask32 & FLAG_E) && (line_pos + (height - 2) == num_flines))
                         tless_exit(0);
         }
 }
@@ -395,22 +389,19 @@ static void buffer_up(int nlines)
         int i;
         int tilde_line;
 
-        if (!(flags & LESS_STATE_PAST_EOF)) {
+        if (!(option_mask32 & LESS_STATE_PAST_EOF)) {
                 if (line_pos - nlines >= 0) {
                         line_pos -= nlines;
                         for (i = 0; i < (height - 1); i++) {
-                                free(buffer[i]);
-                                buffer[i] = xstrdup(flines[line_pos + i]);
+                                buffer[i] = flines[line_pos + i];
                         }
-                }
-                else {
+                } else {
                 /* As the requested number of lines to move was too large, we
                    move one line up at a time until we can't. */
                         while (line_pos != 0) {
                                 line_pos -= 1;
                                 for (i = 0; i < (height - 1); i++) {
-                                        free(buffer[i]);
-                                        buffer[i] = xstrdup(flines[line_pos + i]);
+                                        buffer[i] = flines[line_pos + i];
                                 }
                         }
                 }
@@ -423,19 +414,17 @@ static void buffer_up(int nlines)
                 /* Going backwards nlines lines has taken us to a point where
                    nothing is past the EOF, so we revert to normal. */
                 if (line_pos < num_flines - height + 3) {
-                        flags &= ~LESS_STATE_PAST_EOF;
+                        option_mask32 &= ~LESS_STATE_PAST_EOF;
                         buffer_up(nlines);
-                }
-                else {
+                } else {
                         /* We only move part of the buffer, as the rest
                         is past the EOF */
                         for (i = 0; i < (height - 1); i++) {
-                                free(buffer[i]);
-                                if (i < tilde_line - nlines + 1)
-                                        buffer[i] = xstrdup(flines[line_pos + i]);
-                                else {
+                                if (i < tilde_line - nlines + 1) {
+                                        buffer[i] = flines[line_pos + i];
+                                } else {
                                         if (line_pos >= num_flines - height + 2)
-                                                buffer[i] = xstrdup("~\n");
+                                                buffer[i] = "~";
                                 }
                         }
                 }
@@ -445,7 +434,7 @@ static void buffer_up(int nlines)
 static void buffer_line(int linenum)
 {
         int i;
-        flags &= ~LESS_STATE_PAST_EOF;
+        option_mask32 &= ~LESS_STATE_PAST_EOF;
 
         if (linenum < 0 || linenum > num_flines) {
                 clear_line();
@@ -453,23 +442,20 @@ static void buffer_line(int linenum)
         }
         else if (linenum < (num_flines - height - 2)) {
                 for (i = 0; i < (height - 1); i++) {
-                        free(buffer[i]);
-                        buffer[i] = xstrdup(flines[linenum + i]);
+                        buffer[i] = flines[linenum + i];
                 }
                 line_pos = linenum;
                 buffer_print();
-        }
-        else {
+        } else {
                 for (i = 0; i < (height - 1); i++) {
-                        free(buffer[i]);
                         if (linenum + i < num_flines + 2)
-                                buffer[i] = xstrdup(flines[linenum + i]);
+                                buffer[i] = flines[linenum + i];
                         else
-                                buffer[i] = xstrdup((flags & FLAG_TILDE) ? "\n" : "~\n");
+                                buffer[i] = (option_mask32 & FLAG_TILDE) ? "" : "~";
                 }
                 line_pos = linenum;
                 /* Set past_eof so buffer_down and buffer_up act differently */
-                flags |= LESS_STATE_PAST_EOF;
+                option_mask32 |= LESS_STATE_PAST_EOF;
                 buffer_print();
         }
 }
@@ -490,22 +476,13 @@ static void reinitialise(void)
 
 static void examine_file(void)
 {
-        int newline_offset;
-
         clear_line();
         printf("Examine: ");
-        fgets(filename, 256, inp);
-
-        /* As fgets adds a newline to the end of an input string, we
-           need to remove it */
-        newline_offset = strlen(filename) - 1;
-        filename[newline_offset] = '\0';
-
-        files[num_files] = xstrdup(filename);
+        free(filename);
+        filename = xmalloc_getline(inp);
+        files[num_files] = filename;
         current_file = num_files + 1;
         num_files++;
-
-        flags &= ~LESS_STATE_INP_STDIN;
         reinitialise();
 }
 
@@ -518,10 +495,10 @@ static void change_file(int direction)
 {
         if (current_file != ((direction > 0) ? num_files : 1)) {
                 current_file = direction ? current_file + direction : 1;
-                strcpy(filename, files[current_file - 1]);
+                free(filename);
+                filename = xstrdup(files[current_file - 1]);
                 reinitialise();
-        }
-        else {
+        } else {
                 clear_line();
                 printf("%s%s%s", HIGHLIGHT, (direction > 0) ? "No next file" : "No previous file", NORMAL);
         }
@@ -537,8 +514,7 @@ static void remove_current_file(void)
                         files[i - 2] = files[i - 1];
                 num_files--;
                 buffer_print();
-        }
-        else {
+        } else {
                 change_file(1);
                 for (i = 2; i <= num_files; i++)
                         files[i - 2] = files[i - 1];
@@ -564,7 +540,7 @@ static void colon_process(void)
                 case 'e':
                         examine_file();
                         break;
-#ifdef CONFIG_FEATURE_LESS_FLAGS
+#if ENABLE_FEATURE_LESS_FLAGS
                 case 'f':
                         clear_line();
                         m_status_print();
@@ -587,7 +563,7 @@ static void colon_process(void)
         }
 }
 
-#ifdef CONFIG_FEATURE_LESS_REGEXP
+#if ENABLE_FEATURE_LESS_REGEXP
 /* The below two regular expression handler functions NEED development. */
 
 /* Get a regular expression from the user, and then go through the current
@@ -595,48 +571,50 @@ static void colon_process(void)
 
 static char *process_regex_on_line(char *line, regex_t *pattern, int action)
 {
+/* UNTESTED. LOOKED BUGGY AND LEAKY AS HELL. */
+/* FIXED. NEED TESTING. */
+        /* 'line' should be either returned or free()ed */
+
         /* This function takes the regex and applies it to the line.
            Each part of the line that matches has the HIGHLIGHT
            and NORMAL escape sequences placed around it by
            insert_highlights if action = 1, or has the escape sequences
            removed if action = 0, and then the line is returned. */
         int match_status;
-        char *line2 = xmalloc((sizeof(char) * (strlen(line) + 1)) + 64);
-        char *growline = "";
+        char *line2 = line;
+        char *growline = xstrdup("");
+        char *ng;
         regmatch_t match_structs;
 
-        line2 = xstrdup(line);
-
         match_found = 0;
         match_status = regexec(pattern, line2, 1, &match_structs, 0);
 
         while (match_status == 0) {
-                if (match_found == 0)
-                        match_found = 1;
-
+                match_found = 1;
                 if (action) {
-                        growline = xasprintf("%s%.*s%s%.*s%s", growline,
+                        ng = xasprintf("%s%.*s%s%.*s%s", growline,
                                 match_structs.rm_so, line2, HIGHLIGHT,
                                 match_structs.rm_eo - match_structs.rm_so,
                                 line2 + match_structs.rm_so, NORMAL);
-                }
-                else {
-                        growline = xasprintf("%s%.*s%.*s", growline,
+                } else {
+                        ng = xasprintf("%s%.*s%.*s", growline,
                                 match_structs.rm_so - 4, line2,
                                 match_structs.rm_eo - match_structs.rm_so,
                                 line2 + match_structs.rm_so);
                 }
-
+                free(growline); growline = ng;
                 line2 += match_structs.rm_eo;
                 match_status = regexec(pattern, line2, 1, &match_structs, REG_NOTBOL);
         }
 
-        growline = xasprintf("%s%s", growline, line2);
-
-        return (match_found ? growline : line);
-
+        if (match_found) {
+                ng = xasprintf("%s%s", growline, line2);
+                free(line);
+        } else {
+                ng = line;
+        }
         free(growline);
-        free(line2);
+        return ng;
 }
 
 static void goto_match(int match)
@@ -651,35 +629,33 @@ static void goto_match(int match)
 
 static void regex_process(void)
 {
-        char uncomp_regex[100];
-        char *current_line;
+        char *uncomp_regex;
         int i;
         int j = 0;
         regex_t pattern;
+
         /* Get the uncompiled regular expression from the user */
         clear_line();
-        putchar((flags & LESS_STATE_MATCH_BACKWARDS) ? '?' : '/');
-        uncomp_regex[0] = 0;
-        fgets(uncomp_regex, sizeof(uncomp_regex), inp);
-
-        if (strlen(uncomp_regex) == 1) {
+        putchar((option_mask32 & LESS_STATE_MATCH_BACKWARDS) ? '?' : '/');
+        uncomp_regex = xmalloc_getline(inp);
+        if (!uncomp_regex || !uncomp_regex[0]) {
+                free(uncomp_regex);
                 if (num_matches)
-                        goto_match((flags & LESS_STATE_MATCH_BACKWARDS)
+                        goto_match((option_mask32 & LESS_STATE_MATCH_BACKWARDS)
                                                 ? match_pos - 1 : match_pos + 1);
                 else
                         buffer_print();
                 return;
         }
-        uncomp_regex[strlen(uncomp_regex) - 1] = '\0';
 
         /* Compile the regex and check for errors */
         xregcomp(&pattern, uncomp_regex, 0);
+        free(uncomp_regex);
 
         if (num_matches) {
                 /* Get rid of all the highlights we added previously */
                 for (i = 0; i <= num_flines; i++) {
-                        current_line = process_regex_on_line(flines[i], &old_pattern, 0);
-                        flines[i] = xstrdup(current_line);
+                        flines[i] = process_regex_on_line(flines[i], &old_pattern, 0);
                 }
         }
         old_pattern = pattern;
@@ -692,8 +668,7 @@ static void regex_process(void)
         match_found = 0;
         /* Run the regex on each line of the current file here */
         for (i = 0; i <= num_flines; i++) {
-                current_line = process_regex_on_line(flines[i], &pattern, 1);
-                flines[i] = xstrdup(current_line);
+                flines[i] = process_regex_on_line(flines[i], &pattern, 1);
                 if (match_found) {
                         match_lines = xrealloc(match_lines, (j + 1) * sizeof(int));
                         match_lines[j] = i;
@@ -703,7 +678,7 @@ static void regex_process(void)
 
         num_matches = j;
         if ((match_lines[0] != -1) && (num_flines > height - 2)) {
-                if (flags & LESS_STATE_MATCH_BACKWARDS) {
+                if (option_mask32 & LESS_STATE_MATCH_BACKWARDS) {
                         for (i = 0; i < num_matches; i++) {
                                 if (match_lines[i] > line_pos) {
                                         match_pos = i - 1;
@@ -711,11 +686,9 @@ static void regex_process(void)
                                         break;
                                 }
                         }
-                }
-                else
+                } else
                         buffer_line(match_lines[0]);
-        }
-        else
+        } else
                 buffer_init();
 }
 #endif
@@ -724,9 +697,8 @@ static void number_process(int first_digit)
 {
         int i = 1;
         int num;
-        char num_input[80];
+        char num_input[sizeof(int)*4]; /* more than enough */
         char keypress;
-        char *endptr;
 
         num_input[0] = first_digit;
 
@@ -734,8 +706,11 @@ static void number_process(int first_digit)
         clear_line();
         printf(":%c", first_digit);
 
-        /* Receive input until a letter is given (max 80 chars)*/
-        while((i < 80) && (num_input[i] = tless_getch()) && isdigit(num_input[i])) {
+        /* Receive input until a letter is given */
+        while (i < sizeof(num_input)-1) {
+                num_input[i] = tless_getch();
+                if (!num_input[i] || !isdigit(num_input[i]))
+                        break;
                 putchar(num_input[i]);
                 i++;
         }
@@ -743,8 +718,9 @@ static void number_process(int first_digit)
         /* Take the final letter out of the digits string */
         keypress = num_input[i];
         num_input[i] = '\0';
-        num = strtol(num_input, &endptr, 10);
-        if (endptr==num_input || *endptr!='\0' || num < 1 || num > MAXLINES) {
+        num = bb_strtou(num_input, NULL, 10);
+        /* on format error, num == -1 */
+        if (num < 1 || num > MAXLINES) {
                 buffer_print();
                 return;
         }
@@ -764,16 +740,16 @@ static void number_process(int first_digit)
                 case 'p': case '%':
                         buffer_line(((num / 100) * num_flines) - 1);
                         break;
-#ifdef CONFIG_FEATURE_LESS_REGEXP
+#if ENABLE_FEATURE_LESS_REGEXP
                 case 'n':
                         goto_match(match_pos + num);
                         break;
                 case '/':
-                        flags &= ~LESS_STATE_MATCH_BACKWARDS;
+                        option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
                         regex_process();
                         break;
                 case '?':
-                        flags |= LESS_STATE_MATCH_BACKWARDS;
+                        option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
                         regex_process();
                         break;
 #endif
@@ -782,7 +758,7 @@ static void number_process(int first_digit)
         }
 }
 
-#ifdef CONFIG_FEATURE_LESS_FLAGCS
+#if ENABLE_FEATURE_LESS_FLAGCS
 static void flag_change(void)
 {
         int keypress;
@@ -793,16 +769,16 @@ static void flag_change(void)
 
         switch (keypress) {
                 case 'M':
-                        flags ^= FLAG_M;
+                        option_mask32 ^= FLAG_M;
                         break;
                 case 'm':
-                        flags ^= FLAG_m;
+                        option_mask32 ^= FLAG_m;
                         break;
                 case 'E':
-                        flags ^= FLAG_E;
+                        option_mask32 ^= FLAG_E;
                         break;
                 case '~':
-                        flags ^= FLAG_TILDE;
+                        option_mask32 ^= FLAG_TILDE;
                         break;
                 default:
                         break;
@@ -820,19 +796,19 @@ static void show_flag_status(void)
 
         switch (keypress) {
                 case 'M':
-                        flag_val = flags & FLAG_M;
+                        flag_val = option_mask32 & FLAG_M;
                         break;
                 case 'm':
-                        flag_val = flags & FLAG_m;
+                        flag_val = option_mask32 & FLAG_m;
                         break;
                 case '~':
-                        flag_val = flags & FLAG_TILDE;
+                        flag_val = option_mask32 & FLAG_TILDE;
                         break;
                 case 'N':
-                        flag_val = flags & FLAG_N;
+                        flag_val = option_mask32 & FLAG_N;
                         break;
                 case 'E':
-                        flag_val = flags & FLAG_E;
+                        flag_val = option_mask32 & FLAG_E;
                         break;
                 default:
                         flag_val = 0;
@@ -855,26 +831,31 @@ static void full_repaint(void)
 
 static void save_input_to_file(void)
 {
-        char current_line[256];
+        char *current_line;
         int i;
         FILE *fp;
 
         clear_line();
         printf("Log file: ");
-        fgets(current_line, 256, inp);
-        current_line[strlen(current_line) - 1] = '\0';
-        if (strlen(current_line) > 1) {
-                fp = xfopen(current_line, "w");
+        current_line = xmalloc_getline(inp);
+        if (strlen(current_line) > 0) {
+                fp = fopen(current_line, "w");
+                free(current_line);
+                if (!fp) {
+                        printf("%s%s%s", HIGHLIGHT, "Error opening log file", NORMAL);
+                        return;
+                }
                 for (i = 0; i < num_flines; i++)
-                        fprintf(fp, "%s", flines[i]);
+                        fprintf(fp, "%s\n", flines[i]);
                 fclose(fp);
                 buffer_print();
+                return;
         }
-        else
-                printf("%s%s%s", HIGHLIGHT, "No log file", NORMAL);
+        free(current_line);
+        printf("%s%s%s", HIGHLIGHT, "No log file", NORMAL);
 }
 
-#ifdef CONFIG_FEATURE_LESS_MARKS
+#if ENABLE_FEATURE_LESS_MARKS
 static void add_mark(void)
 {
         int letter;
@@ -892,8 +873,7 @@ static void add_mark(void)
                 mark_lines[num_marks][0] = letter;
                 mark_lines[num_marks][1] = line_pos;
                 num_marks++;
-        }
-        else {
+        } else {
                 clear_line();
                 printf("%s%s%s", HIGHLIGHT, "Invalid mark letter", NORMAL);
         }
@@ -917,14 +897,13 @@ static void goto_mark(void)
                         }
                 if ((num_marks == 14) && (letter != mark_lines[14][0]))
                         printf("%s%s%s", HIGHLIGHT, "Mark not set", NORMAL);
-        }
-        else
+        } else
                 printf("%s%s%s", HIGHLIGHT, "Invalid mark letter", NORMAL);
 }
 #endif
 
 
-#ifdef CONFIG_FEATURE_LESS_BRACKETS
+#if ENABLE_FEATURE_LESS_BRACKETS
 
 static char opp_bracket(char bracket)
 {
@@ -977,8 +956,7 @@ static void match_left_bracket(char bracket)
                 printf("%s%s%s", HIGHLIGHT, "No bracket in bottom line", NORMAL);
                 printf("%s", flines[line_pos + height]);
                 sleep(4);
-        }
-        else {
+        } else {
                 for (i = line_pos + height - 2; i >= 0; i--) {
                         if (strchr(flines[i], opp_bracket(bracket)) != NULL) {
                                 bracket_line = i;
@@ -993,7 +971,7 @@ static void match_left_bracket(char bracket)
         }
 }
 
-#endif  /* CONFIG_FEATURE_LESS_BRACKETS */
+#endif  /* FEATURE_LESS_BRACKETS */
 
 static void keypress_process(int keypress)
 {
@@ -1031,7 +1009,7 @@ static void keypress_process(int keypress)
                 case 'q': case 'Q':
                         tless_exit(0);
                         break;
-#ifdef CONFIG_FEATURE_LESS_MARKS
+#if ENABLE_FEATURE_LESS_MARKS
                 case 'm':
                         add_mark();
                         buffer_print();
@@ -1048,21 +1026,20 @@ static void keypress_process(int keypress)
                         full_repaint();
                         break;
                 case 's':
-                        if (flags & LESS_STATE_INP_STDIN)
-                                save_input_to_file();
+                        save_input_to_file();
                         break;
                 case 'E':
                         examine_file();
                         break;
-#ifdef CONFIG_FEATURE_LESS_FLAGS
+#if ENABLE_FEATURE_LESS_FLAGS
                 case '=':
                         clear_line();
                         m_status_print();
                         break;
 #endif
-#ifdef CONFIG_FEATURE_LESS_REGEXP
+#if ENABLE_FEATURE_LESS_REGEXP
                 case '/':
-                        flags &= ~LESS_STATE_MATCH_BACKWARDS;
+                        option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
                         regex_process();
                         break;
                 case 'n':
@@ -1072,11 +1049,11 @@ static void keypress_process(int keypress)
                         goto_match(match_pos - 1);
                         break;
                 case '?':
-                        flags |= LESS_STATE_MATCH_BACKWARDS;
+                        option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
                         regex_process();
                         break;
 #endif
-#ifdef CONFIG_FEATURE_LESS_FLAGCS
+#if ENABLE_FEATURE_LESS_FLAGCS
                 case '-':
                         flag_change();
                         buffer_print();
@@ -1085,7 +1062,7 @@ static void keypress_process(int keypress)
                         show_flag_status();
                         break;
 #endif
-#ifdef CONFIG_FEATURE_LESS_BRACKETS
+#if ENABLE_FEATURE_LESS_BRACKETS
                 case '{': case '(': case '[':
                         match_right_bracket(keypress);
                         break;
@@ -1104,30 +1081,42 @@ static void keypress_process(int keypress)
                 number_process(keypress);
 }
 
-int less_main(int argc, char **argv) {
+static void sig_catcher(int sig ATTRIBUTE_UNUSED)
+{
+        set_tty_cooked();
+        exit(1);
+}
 
+int less_main(int argc, char **argv)
+{
         int keypress;
 
-        flags = getopt32(argc, argv, "EMmN~");
-
+        getopt32(argc, argv, "EMmN~");
         argc -= optind;
         argv += optind;
         files = argv;
         num_files = argc;
 
         if (!num_files) {
-                if (ttyname(STDIN_FILENO) == NULL)
-                        flags |= LESS_STATE_INP_STDIN;
-                else {
+                if (isatty(STDIN_FILENO)) {
+                        /* Just "less"? No file and no redirection? */
                         bb_error_msg("missing filename");
                         bb_show_usage();
                 }
-        }
+        } else
+                filename = xstrdup(files[0]);
+
+        /* FIXME: another popular pager, most, detects when stdout
+         * is not a tty and turns into cat */
+        inp = xfopen(CURRENT_TTY, "r");
 
-        strcpy(filename, (flags & LESS_STATE_INP_STDIN) ? bb_msg_standard_input : files[0]);
-        get_terminal_width_height(0, &width, &height);
+        get_terminal_width_height(fileno(inp), &width, &height);
         data_readlines();
+
+        signal(SIGTERM, sig_catcher);
+        signal(SIGINT, sig_catcher);
         tcgetattr(fileno(inp), &term_orig);
+
         term_vi = term_orig;
         term_vi.c_lflag &= (~ICANON & ~ECHO);
         term_vi.c_iflag &= (~IXON & ~ICRNL);