2 files changed, 238 insertions, 253 deletions

diff --git a/libbb/xregcomp.c b/libbb/xregcomp.c
index 4bcb9aedf..6e9a29f49 100644
--- a/libbb/xregcomp.c
+++ b/libbb/xregcomp.c
@@ -8,16 +8,13 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include <stdio.h>
 #include "libbb.h"
 #include "xregex.h"
 
-
-
 void xregcomp(regex_t *preg, const char *regex, int cflags)
 {
-        int ret;
-        if ((ret = regcomp(preg, regex, cflags)) != 0) {
+        int ret = regcomp(preg, regex, cflags);
+        if (ret) {
                 int errmsgsz = regerror(ret, preg, NULL, 0);
                 char *errmsg = xmalloc(errmsgsz);
                 regerror(ret, preg, errmsg, errmsgsz);
diff --git a/miscutils/less.c b/miscutils/less.c
index 73500671d..6843dddcb 100644
--- a/miscutils/less.c
+++ b/miscutils/less.c
@@ -8,30 +8,20 @@
  */
 
 /*
- *      This program needs a lot of development, so consider it in a beta stage
- *      at best.
+ * TODO:
+ * - Add more regular expression support - search modifiers, certain matches, etc.
+ * - Add more complex bracket searching - currently, nested brackets are
+ * not considered.
+ * - Add support for "F" as an input. This causes less to act in
+ * a similar way to tail -f.
+ * - Allow horizontal scrolling.
  *
- *      TODO:
- *      - Add more regular expression support - search modifiers, certain matches, etc.
- *      - Add more complex bracket searching - currently, nested brackets are
- *      not considered.
- *      - Add support for "F" as an input. This causes less to act in
- *      a similar way to tail -f.
- *      - Check for binary files, and prompt the user if a binary file
- *      is detected.
- *      - Allow horizontal scrolling. Currently, lines simply continue onto
- *      the next line, per the terminal's discretion
- *
- *      Notes:
- *      - filename is an array and not a pointer because that avoids all sorts
- *      of complications involving the fact that something that is pointed to
- *      will be changed if the pointer is changed.
- *      - the inp file pointer is used so that keyboard input works after
- *      redirected input has been read from stdin
-*/
+ * Notes:
+ * - the inp file pointer is used so that keyboard input works after
+ * redirected input has been read from stdin
+ */
 
 #include "busybox.h"
-
 #if ENABLE_FEATURE_LESS_REGEXP
 #include "xregex.h"
 #endif
@@ -70,12 +60,13 @@ static int height;
 static int width;
 static char **files;
 static char *filename;
-static char **buffer;
+static const char **buffer;
 static char **flines;
 static int current_file = 1;
 static int line_pos;
 static int num_flines;
 static int num_files = 1;
+static const char *empty_line_marker = "~";
 
 /* Command line options */
 #define FLAG_E 1
@@ -84,7 +75,6 @@ static int num_files = 1;
 #define FLAG_N (1<<3)
 #define FLAG_TILDE (1<<4)
 /* hijack command line options variable for internal state vars */
-#define LESS_STATE_PAST_EOF  (1<<5)
 #define LESS_STATE_MATCH_BACKWARDS (1<<6)
 
 #if ENABLE_FEATURE_LESS_MARKS
@@ -93,11 +83,11 @@ static int num_marks;
 #endif
 
 #if ENABLE_FEATURE_LESS_REGEXP
-static int match_found;
 static int *match_lines;
 static int match_pos;
 static int num_matches;
-static regex_t old_pattern;
+static regex_t pattern;
+static int pattern_valid;
 #endif
 
 /* Needed termios structures */
@@ -174,52 +164,57 @@ static void data_readlines(void)
         unsigned i;
         unsigned n = 1;
         int w = width;
-        char *last_nl = (char*)1; /* "not NULL" */
-        char *current_line;
+        /* "remained unused space" in a line (0 if line fills entire width) */
+        int rem, last_rem = 1; /* "not 0" */
+        char *current_line, *p;
         FILE *fp;
 
         fp = filename ? xfopen(filename, "r") : stdin;
         flines = NULL;
         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);
+                p = current_line;
+                rem = w - 1;
+                do {
+                        int c = getc(fp);
+                        if (c == EOF) break;
+                        if (c == '\n') break;
+                        /* NUL is substituted by '\n'! */
+                        if (c == '\0') c = '\n';
+                        *p++ = c;
+                } while (--rem);
+                *p = '\0';
                 if (fp != stdin)
                         die_if_ferror(fp, filename);
 
-                /* 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" */
+                /* Corner case: linewrap with only "" wrapping to next line */
+                /* Looks ugly on screen, so we do not store this empty line */
+                if (!last_rem && !current_line[0]) {
+                        last_rem = 1; /* "not 0" */
                         n++;
                         goto again;
                 }
-                last_nl = last_char_is(current_line, '\n');
-                if (last_nl)
-                        *last_nl = '\0';
+                last_rem = rem;
                 if (option_mask32 & FLAG_N) {
                         flines[i] = xasprintf((n <= 99999) ? "%5u %s" : "%05u %s",
                                                 n % 100000, current_line);
                         free(current_line);
-                        if (last_nl)
+                        if (rem)
                                 n++;
                 } else {
                         flines[i] = xrealloc(current_line, strlen(current_line)+1);
                 }
         }
-        num_flines = i - 2;
+        num_flines = i - 1; /* buggie: 'num_flines' must be 'max_fline' */
 
         /* Reset variables for a new file */
 
         line_pos = 0;
-        option_mask32 &= ~LESS_STATE_PAST_EOF;
 
         fclose(fp);
 }
@@ -238,36 +233,28 @@ static void m_status_print(void)
 {
         int percentage;
 
-        if (!(option_mask32 & LESS_STATE_PAST_EOF)) {
-                if (!line_pos) {
-                        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 {
-                                printf("%s%s lines %i-%i/%i ", HIGHLIGHT,
-                                        filename, line_pos + 1, line_pos + height - 1,
-                                        num_flines + 1);
-                        }
-                } else {
-                        printf("%s %s lines %i-%i/%i ", HIGHLIGHT, filename,
+        if (!line_pos) {
+                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);
-                }
-
-                if (line_pos == num_flines - height + 2) {
-                        printf("(END) %s", NORMAL);
-                        if ((num_files > 1) && (current_file != num_files))
-                                printf("%s- Next: %s%s", HIGHLIGHT, files[current_file], NORMAL);
                 } else {
-                        percentage = calc_percent();
-                        printf("%i%% %s", percentage, NORMAL);
+                        printf("%s%s lines %i-%i/%i ", HIGHLIGHT,
+                                filename, line_pos + 1, line_pos + height - 1,
+                                num_flines + 1);
                 }
         } else {
-                printf("%s%s lines %i-%i/%i (END) ", HIGHLIGHT, filename,
-                                line_pos + 1, num_flines + 1, num_flines + 1);
+                printf("%s %s lines %i-%i/%i ", HIGHLIGHT, filename,
+                        line_pos + 1, line_pos + height - 1, num_flines + 1);
+        }
+
+        if (line_pos >= num_flines - height + 2) {
+                printf("(END) %s", NORMAL);
                 if ((num_files > 1) && (current_file != num_files))
-                        printf("- Next: %s", files[current_file]);
-                printf("%s", NORMAL);
+                        printf("%s- Next: %s%s", HIGHLIGHT, files[current_file], NORMAL);
+        } else {
+                percentage = calc_percent();
+                printf("%i%% %s", percentage, NORMAL);
         }
 }
 
@@ -315,22 +302,123 @@ static void status_print(void)
 #endif
 }
 
+static char controls[] =
+        /**/"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
+        "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
+        "\x7f\x9b"; /* DEL and infamous Meta-ESC :( */
+static char ctrlconv[] =
+        /* Note that on input NUL is converted to '\n' ('\x0a') */
+        /* Therefore we subst '\n' with '@', not 'J' */
+        "\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x40\x4b\x4c\x4d\x4e\x4f"
+        "\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f";
+
+static void print_found(const char *line)
+{
+        int match_status;
+        int eflags;
+        char *growline;
+        regmatch_t match_structs;
+
+        char buf[width];
+        const char *str = line;
+        char *p = buf;
+        size_t n;
+
+        while (*str) {
+                n = strcspn(str, controls);
+                if (n) {
+                        if (!str[n]) break;
+                        memcpy(p, str, n);
+                        p += n;
+                        str += n;
+                }
+                n = strspn(str, controls);
+                memset(p, '.', n);
+                p += n;
+                str += n;
+                /*
+                do {
+                        if (*str == '\x7f') { *p++ = '?'; str++; }
+                        else if (*str == '\x9b') { *p++ = '{'; str++; }
+                        else *p++ = ctrlconv[(unsigned char)*str++];
+                } while (--n);
+                */
+        }
+        strcpy(p, str);
+
+        /* buf[] holds quarantined version of str */
+
+        /* Each part of the line that matches has the HIGHLIGHT
+           and NORMAL escape sequences placed around it.
+           NB: we regex against line, but insert text
+           from quarantined copy (buf[]) */
+        str = buf;
+        growline = NULL;
+        eflags = 0;
+        goto start;
+
+        while (match_status == 0) {
+                char *new = xasprintf("%s" "%.*s" "%s" "%.*s" "%s",
+                                growline ? : "",
+                                match_structs.rm_so, str,
+                                HIGHLIGHT,
+                                match_structs.rm_eo - match_structs.rm_so,
+                                                str + match_structs.rm_so,
+                                NORMAL);
+                free(growline); growline = new;
+                str += match_structs.rm_eo;
+                line += match_structs.rm_eo;
+                eflags = REG_NOTBOL;
+ start:
+                /* Most of the time doesn't find the regex, optimize for that */
+                match_status = regexec(&pattern, line, 1, &match_structs, eflags);
+        }
+
+        if (!growline) {
+                puts(str);
+                return;
+        }
+        printf("%s%s\n", growline, str);
+        free(growline);
+}
+
+static void print_ascii(const char *str)
+{
+        char buf[width];
+        char *p;
+        size_t n;
+
+        while (*str) {
+                n = strcspn(str, controls);
+                if (n) {
+                        if (!str[n]) break;
+                        printf("%.*s", n, str);
+                        str += n;
+                }
+                n = strspn(str, controls);
+                p = buf;
+                do {
+                        if (*str == '\x7f') { *p++ = '?'; str++; }
+                        else if (*str == '\x9b') { *p++ = '{'; str++; }
+                        else *p++ = ctrlconv[(unsigned char)*str++];
+                } while (--n);
+                *p = '\0';
+                printf("%s%s%s", HIGHLIGHT, buf, NORMAL);
+        }
+        puts(str);
+}
+
 /* Print the buffer */
 static void buffer_print(void)
 {
         int i;
 
         printf("%s", CLEAR);
-        if (num_flines >= height - 2) {
-                for (i = 0; i < height - 1; i++)
-                        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\n", width, buffer[i]);
-        }
-
+        for (i = 0; i < height - 1; i++)
+                if (pattern_valid)
+                        print_found(buffer[i]);
+                else
+                        print_ascii(buffer[i]);
         status_print();
 }
 
@@ -339,20 +427,20 @@ static void buffer_init(void)
 {
         int i;
 
-        if (buffer == NULL) {
+        if (!buffer) {
                 /* malloc the number of lines needed for the buffer */
                 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++) {
+        for (i = 0; i < height - 1 && i <= num_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] = "";
+        for (; i < height - 1; i++) {
+                buffer[i] = empty_line_marker;
         }
 }
 
@@ -361,72 +449,38 @@ static void buffer_down(int nlines)
 {
         int i;
 
-        if (!(option_mask32 & LESS_STATE_PAST_EOF)) {
-                if (line_pos + (height - 3) + nlines < num_flines) {
-                        line_pos += nlines;
+        if (line_pos + (height - 3) + nlines < num_flines) {
+                line_pos += nlines;
+                for (i = 0; i < (height - 1); i++) {
+                        buffer[i] = flines[line_pos + i];
+                }
+        } 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++) {
                                 buffer[i] = flines[line_pos + i];
                         }
-                } 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++) {
-                                        buffer[i] = flines[line_pos + i];
-                                }
-                        }
                 }
-
-                /* We exit if the -E flag has been set */
-                if ((option_mask32 & FLAG_E) && (line_pos + (height - 2) == num_flines))
-                        tless_exit(0);
         }
+
+        /* We exit if the -E flag has been set */
+        if ((option_mask32 & FLAG_E) && (line_pos + (height - 2) == num_flines))
+                tless_exit(0);
 }
 
 static void buffer_up(int nlines)
 {
         int i;
-        int tilde_line;
 
-        if (!(option_mask32 & LESS_STATE_PAST_EOF)) {
-                if (line_pos - nlines >= 0) {
-                        line_pos -= nlines;
-                        for (i = 0; i < (height - 1); i++) {
-                                buffer[i] = flines[line_pos + i];
-                        }
-                } 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++) {
-                                        buffer[i] = flines[line_pos + i];
-                                }
-                        }
-                }
-        }
-        else {
-                /* Work out where the tildes start */
-                tilde_line = num_flines - line_pos + 3;
-
-                line_pos -= 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) {
-                        option_mask32 &= ~LESS_STATE_PAST_EOF;
-                        buffer_up(nlines);
+        line_pos -= nlines;
+        if (line_pos < 0) line_pos = 0;
+        for (i = 0; i < height - 1; i++) {
+                if (line_pos + i <= num_flines) {
+                        buffer[i] = flines[line_pos + i];
                 } else {
-                        /* We only move part of the buffer, as the rest
-                        is past the EOF */
-                        for (i = 0; i < (height - 1); i++) {
-                                if (i < tilde_line - nlines + 1) {
-                                        buffer[i] = flines[line_pos + i];
-                                } else {
-                                        if (line_pos >= num_flines - height + 2)
-                                                buffer[i] = "~";
-                                }
-                        }
+                        buffer[i] = empty_line_marker;
                 }
         }
 }
@@ -434,28 +488,19 @@ static void buffer_up(int nlines)
 static void buffer_line(int linenum)
 {
         int i;
-        option_mask32 &= ~LESS_STATE_PAST_EOF;
 
         if (linenum < 0 || linenum > num_flines) {
                 clear_line();
                 printf("%s%s%i%s", HIGHLIGHT, "Cannot seek to line number ", linenum + 1, NORMAL);
-        }
-        else if (linenum < (num_flines - height - 2)) {
-                for (i = 0; i < (height - 1); i++) {
-                        buffer[i] = flines[linenum + i];
-                }
-                line_pos = linenum;
-                buffer_print();
         } else {
-                for (i = 0; i < (height - 1); i++) {
-                        if (linenum + i < num_flines + 2)
+                for (i = 0; i < height - 1; i++) {
+                        if (linenum + i <= num_flines)
                                 buffer[i] = flines[linenum + i];
-                        else
-                                buffer[i] = (option_mask32 & FLAG_TILDE) ? "" : "~";
+                        else {
+                                buffer[i] = empty_line_marker;
+                        }
                 }
                 line_pos = linenum;
-                /* Set past_eof so buffer_down and buffer_up act differently */
-                option_mask32 |= LESS_STATE_PAST_EOF;
                 buffer_print();
         }
 }
@@ -563,76 +608,37 @@ static void colon_process(void)
         }
 }
 
-#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
-   file line by line, running a processing regex function on each one. */
-
-static char *process_regex_on_line(char *line, regex_t *pattern, int action)
+static int normalize_match_pos(int match)
 {
-/* 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 = line;
-        char *growline = xstrdup("");
-        char *ng;
-        regmatch_t match_structs;
-
-        match_found = 0;
-        match_status = regexec(pattern, line2, 1, &match_structs, 0);
-
-        while (match_status == 0) {
-                match_found = 1;
-                if (action) {
-                        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 {
-                        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);
-        }
-
-        if (match_found) {
-                ng = xasprintf("%s%s", growline, line2);
-                free(line);
-        } else {
-                ng = line;
-        }
-        free(growline);
-        return ng;
+        match_pos = match;
+        if (match < 0)
+                return (match_pos = 0);
+        if (match >= num_matches)
+{
+                match_pos = num_matches - 1;
+}
+        return match_pos;
 }
 
+#if ENABLE_FEATURE_LESS_REGEXP
 static void goto_match(int match)
 {
-        /* This goes to a specific match - all line positions of matches are
-           stored within the match_lines[] array. */
-        if ((match < num_matches) && (match >= 0)) {
-                buffer_line(match_lines[match]);
-                match_pos = match;
-        }
+        buffer_line(match_lines[normalize_match_pos(match)]);
 }
 
 static void regex_process(void)
 {
         char *uncomp_regex;
-        int i;
-        int j = 0;
-        regex_t pattern;
+
+        /* Reset variables */
+        match_lines = xrealloc(match_lines, sizeof(int));
+        match_lines[0] = -1;
+        match_pos = 0;
+        num_matches = 0;
+        if (pattern_valid) {
+                regfree(&pattern);
+                pattern_valid = 0;
+        }
 
         /* Get the uncompiled regular expression from the user */
         clear_line();
@@ -640,56 +646,33 @@ static void regex_process(void)
         uncomp_regex = xmalloc_getline(inp);
         if (!uncomp_regex || !uncomp_regex[0]) {
                 free(uncomp_regex);
-                if (num_matches)
-                        goto_match((option_mask32 & LESS_STATE_MATCH_BACKWARDS)
-                                                ? match_pos - 1 : match_pos + 1);
-                else
-                        buffer_print();
+                buffer_print();
                 return;
         }
 
         /* Compile the regex and check for errors */
         xregcomp(&pattern, uncomp_regex, 0);
         free(uncomp_regex);
+        pattern_valid = 1;
 
-        if (num_matches) {
-                /* Get rid of all the highlights we added previously */
-                for (i = 0; i <= num_flines; i++) {
-                        flines[i] = process_regex_on_line(flines[i], &old_pattern, 0);
+        /* Run the regex on each line of the current file */
+        for (match_pos = 0; match_pos <= num_flines; match_pos++) {
+                if (regexec(&pattern, flines[match_pos], 0, NULL, 0) == 0) {
+                        match_lines = xrealloc(match_lines, (num_matches+1) * sizeof(int));
+                        match_lines[num_matches++] = match_pos;
                 }
         }
-        old_pattern = pattern;
 
-        /* Reset variables */
-        match_lines = xrealloc(match_lines, sizeof(int));
-        match_lines[0] = -1;
-        match_pos = 0;
-        num_matches = 0;
-        match_found = 0;
-        /* Run the regex on each line of the current file here */
-        for (i = 0; i <= num_flines; i++) {
-                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;
-                        j++;
-                }
+        if (num_matches == 0 || num_flines <= height - 2) {
+                buffer_print();
+                return;
         }
-
-        num_matches = j;
-        if ((match_lines[0] != -1) && (num_flines > height - 2)) {
-                if (option_mask32 & LESS_STATE_MATCH_BACKWARDS) {
-                        for (i = 0; i < num_matches; i++) {
-                                if (match_lines[i] > line_pos) {
-                                        match_pos = i - 1;
-                                        buffer_line(match_lines[match_pos]);
-                                        break;
-                                }
-                        }
-                } else
-                        buffer_line(match_lines[0]);
-        } else
-                buffer_init();
+        for (match_pos = 0; match_pos < num_matches; match_pos++) {
+                if (match_lines[match_pos] > line_pos)
+                        break;
+        }
+        if (option_mask32 & LESS_STATE_MATCH_BACKWARDS) match_pos--;
+        buffer_line(match_lines[normalize_match_pos(match_pos)]);
 }
 #endif
 
@@ -1111,11 +1094,16 @@ int less_main(int argc, char **argv)
         inp = xfopen(CURRENT_TTY, "r");
 
         get_terminal_width_height(fileno(inp), &width, &height);
+        if (width < 10 || height < 3)
+                bb_error_msg_and_die("too narrow here");
+
+        if (option_mask32 & FLAG_TILDE) empty_line_marker = "";
+
         data_readlines();
 
+        tcgetattr(fileno(inp), &term_orig);
         signal(SIGTERM, sig_catcher);
         signal(SIGINT, sig_catcher);
-        tcgetattr(fileno(inp), &term_orig);
 
         term_vi = term_orig;
         term_vi.c_lflag &= (~ICANON & ~ECHO);