xargs: code shrink -15 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 79 insertions, 80 deletions

diff --git a/findutils/xargs.c b/findutils/xargs.c
index 9133b8f6c..25a785336 100644
--- a/findutils/xargs.c
+++ b/findutils/xargs.c
@@ -122,53 +122,49 @@ typedef struct xlist_t {
         char xstr[1];
 } xlist_t;
 
-static smallint eof_stdin_detected;
-
-#define ISBLANK(c) ((c) == ' ' || (c) == '\t')
-#define ISSPACE(c) (ISBLANK(c) || (c) == '\n' || (c) == '\r' \
-                    || (c) == '\f' || (c) == '\v')
+/* In POSIX/C locale isspace is only these chars: "\t\n\v\f\r" and space.
+ * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
+ */
+#define ISSPACE(a) ({ unsigned char xargs__isspace = (a) - 9; xargs__isspace == (' ' - 9) || xargs__isspace <= (13 - 9); })
 
 #if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
-static xlist_t *process_stdin(xlist_t *list_arg,
+static xlist_t* process_stdin(xlist_t *list_arg,
         const char *eof_str, size_t mc, char *buf)
 {
 #define NORM      0
 #define QUOTE     1
 #define BACKSLASH 2
 #define SPACE     4
-
-        char *s = NULL;         /* start word */
-        char *p = NULL;         /* pointer to end word */
+        char *s = NULL;         /* start of the word */
+        char *p = NULL;         /* pointer to end of the word */
         char q = '\0';          /* quote char */
         char state = NORM;
         char eof_str_detected = 0;
-        size_t line_l = 0;      /* size loaded args line */
-        int c;                  /* current char */
+        size_t line_l = 0;      /* size of loaded args */
         xlist_t *cur;
         xlist_t *prev;
 
         prev = cur = list_arg;
-        while (1) {
-                if (!cur) break;
+        while (cur) {
                 prev = cur;
                 line_l += cur->length;
                 cur = cur->link;
         }
 
-        while (!eof_stdin_detected) {
-                c = getchar();
+        while (1) {
+                int c = getchar();
                 if (c == EOF) {
-                        eof_stdin_detected = 1;
                         if (s)
                                 goto unexpected_eof;
                         break;
                 }
-                if (eof_str_detected)
+                if (eof_str_detected) /* skip till EOF */
                         continue;
                 if (state == BACKSLASH) {
                         state = NORM;
                         goto set;
-                } else if (state == QUOTE) {
+                }
+                if (state == QUOTE) {
                         if (c != q)
                                 goto set;
                         q = '\0';
@@ -202,7 +198,7 @@ static xlist_t *process_stdin(xlist_t *list_arg,
                                 bb_error_msg_and_die("unmatched %s quote",
                                         q == '\'' ? "single" : "double");
                         }
-                        /* word loaded */
+                        /* A full word is loaded */
                         if (eof_str) {
                                 eof_str_detected = (strcmp(s, eof_str) == 0);
                         }
@@ -220,10 +216,8 @@ static xlist_t *process_stdin(xlist_t *list_arg,
                                 }
                                 prev = cur;
                                 line_l += length;
-                                if (line_l > mc) {
-                                        /* stop memory usage :-) */
+                                if (line_l > mc) /* limit stop memory usage */
                                         break;
-                                }
                         }
                         s = NULL;
                         state = NORM;
@@ -233,33 +227,32 @@ static xlist_t *process_stdin(xlist_t *list_arg,
 }
 #else
 /* The variant does not support single quotes, double quotes or backslash */
-static xlist_t *process_stdin(xlist_t *list_arg,
+static xlist_t* process_stdin(xlist_t *list_arg,
                 const char *eof_str, size_t mc, char *buf)
 {
-
-        int c;                  /* current char */
         char eof_str_detected = 0;
-        char *s = NULL;         /* start word */
-        char *p = NULL;         /* pointer to end word */
-        size_t line_l = 0;      /* size loaded args line */
+        char *s = NULL;         /* start of the word */
+        char *p = NULL;         /* pointer to end of the word */
+        size_t line_l = 0;      /* size of loaded args */
         xlist_t *cur;
         xlist_t *prev;
 
         prev = cur = list_arg;
-        while (1) {
-                if (!cur) break;
+        while (cur) {
                 prev = cur;
                 line_l += cur->length;
                 cur = cur->link;
         }
 
-        while (!eof_stdin_detected) {
-                c = getchar();
+        while (1) {
+                int c = getchar();
                 if (c == EOF) {
-                        eof_stdin_detected = 1;
+                        if (s == NULL)
+                                break;
                 }
-                if (eof_str_detected)
+                if (eof_str_detected) { /* skip till EOF */
                         continue;
+                }
                 if (c == EOF || ISSPACE(c)) {
                         if (s == NULL)
                                 continue;
@@ -271,7 +264,7 @@ static xlist_t *process_stdin(xlist_t *list_arg,
                         bb_error_msg_and_die("argument line too long");
                 *p++ = (c == EOF ? '\0' : c);
                 if (c == EOF) { /* word's delimiter or EOF detected */
-                        /* word loaded */
+                        /* A full word is loaded */
                         if (eof_str) {
                                 eof_str_detected = (strcmp(s, eof_str) == 0);
                         }
@@ -289,12 +282,10 @@ static xlist_t *process_stdin(xlist_t *list_arg,
                                 }
                                 prev = cur;
                                 line_l += length;
-                                if (line_l > mc) {
-                                        /* stop memory usage :-) */
+                                if (line_l > mc) /* limit stop memory usage */
                                         break;
-                                }
-                                s = NULL;
                         }
+                        s = NULL;
                 }
         }
         return list_arg;
@@ -325,28 +316,25 @@ static int xargs_ask_confirmation(void)
 #endif /* FEATURE_XARGS_SUPPORT_CONFIRMATION */
 
 #if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
-static xlist_t *process0_stdin(xlist_t *list_arg,
+static xlist_t* process0_stdin(xlist_t *list_arg,
                 const char *eof_str UNUSED_PARAM, size_t mc, char *buf)
 {
-        int c;                  /* current char */
-        char *s = NULL;         /* start word */
-        char *p = NULL;         /* pointer to end word */
-        size_t line_l = 0;      /* size loaded args line */
+        char *s = NULL;         /* start of the word */
+        char *p = NULL;         /* pointer to end of the word */
+        size_t line_l = 0;      /* size of loaded args */
         xlist_t *cur;
         xlist_t *prev;
 
         prev = cur = list_arg;
-        while (1) {
-                if (!cur) break;
+        while (cur) {
                 prev = cur;
                 line_l += cur->length;
                 cur = cur->link;
         }
 
-        while (!eof_stdin_detected) {
-                c = getchar();
+        while (1) {
+                int c = getchar();
                 if (c == EOF) {
-                        eof_stdin_detected = 1;
                         if (s == NULL)
                                 break;
                         c = '\0';
@@ -357,7 +345,7 @@ static xlist_t *process0_stdin(xlist_t *list_arg,
                         bb_error_msg_and_die("argument line too long");
                 *p++ = c;
                 if (c == '\0') {   /* word's delimiter or EOF detected */
-                        /* word loaded */
+                        /* A full word is loaded */
                         size_t length = (p - buf);
                         /* Dont xzalloc - it can be quite big */
                         cur = xmalloc(offsetof(xlist_t, xstr) + length);
@@ -371,10 +359,8 @@ static xlist_t *process0_stdin(xlist_t *list_arg,
                         }
                         prev = cur;
                         line_l += length;
-                        if (line_l > mc) {
-                                /* stop memory usage :-) */
+                        if (line_l > mc) /* limit stop memory usage */
                                 break;
-                        }
                         s = NULL;
                 }
         }
@@ -412,12 +398,11 @@ enum {
 int xargs_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int xargs_main(int argc, char **argv)
 {
-        char **args;
-        int i, n;
         xlist_t *list = NULL;
-        xlist_t *cur;
         int child_error = 0;
-        char *max_args, *max_chars;
+        char *max_args;
+        char *max_chars;
+        char *buf;
         int n_max_arg;
         const char *eof_str = NULL;
         unsigned opt;
@@ -441,15 +426,12 @@ int xargs_main(int argc, char **argv)
 
         argv += optind;
         argc -= optind;
-        if (!argc) {
+        if (!argv[0]) {
                 /* default behavior is to echo all the filenames */
-                *argv = (char*)"echo";
+                *--argv = (char*)"echo";
                 argc++;
         }
 
-        n_max_chars = ARG_MAX; /* might be calling sysconf(_SC_ARG_MAX) */
-        if (n_max_chars < 4*1024); /* paranoia */
-                n_max_chars = LONG_MAX;
         /* The Open Group Base Specifications Issue 6:
          * "The xargs utility shall limit the command line length such that
          * when the command line is invoked, the combined argument
@@ -457,27 +439,32 @@ int xargs_main(int argc, char **argv)
          * in the System Interfaces volume of IEEE Std 1003.1-2001)
          * shall not exceed {ARG_MAX}-2048 bytes".
          */
+        n_max_chars = ARG_MAX; /* might be calling sysconf(_SC_ARG_MAX) */
+        if (n_max_chars < 4*1024); /* paranoia */
+                n_max_chars = 4*1024;
         n_max_chars -= 2048;
         /* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
-         * have it at 1 meg).  Things will work fine with a large ARG_MAX but it
-         * will probably hurt the system more than it needs to; an array of this
-         * size is allocated.
+         * have it at 1 meg).  Things will work fine with a large ARG_MAX
+         * but it will probably hurt the system more than it needs to;
+         * an array of this size is allocated.
          */
         if (n_max_chars > 20 * 1024)
                 n_max_chars = 20 * 1024;
 
         if (opt & OPT_UPTO_SIZE) {
+                int i;
                 size_t n_chars = 0;
                 n_max_chars = xatoul_range(max_chars, 1, n_max_chars);
-                for (i = 0; i < argc; i++) {
-                        n_chars += strlen(*argv) + 1;
+                for (i = 0; argv[i]; i++) {
+                        n_chars += strlen(argv[i]) + 1;
                 }
-                if (n_max_chars <= n_chars) {
+                n_max_chars -= n_chars;
+                if ((ssize_t)n_max_chars <= 0) {
                         bb_error_msg_and_die("can't fit single argument within argument list size limit");
                 }
-                n_max_chars -= n_chars;
         }
-        max_chars = xmalloc(n_max_chars);
+
+        buf = xmalloc(n_max_chars);
 
         if (opt & OPT_UPTO_NUMBER) {
                 n_max_arg = xatoul_range(max_args, 1, INT_MAX);
@@ -485,10 +472,14 @@ int xargs_main(int argc, char **argv)
                 n_max_arg = n_max_chars;
         }
 
-        while ((list = read_args(list, eof_str, n_max_chars, max_chars)) != NULL ||
-                !(opt & OPT_NO_EMPTY))
-        {
+        while ((list = read_args(list, eof_str, n_max_chars, buf)) != NULL
+         ||    !(opt & OPT_NO_EMPTY)
+        ) {
+                char **args;
+                xlist_t *cur;
+                int i, n;
                 size_t n_chars = 0;
+
                 opt |= OPT_NO_EMPTY;
                 n = 0;
 #if ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
@@ -510,15 +501,14 @@ int xargs_main(int argc, char **argv)
                                 break;
                         }
                 }
-#endif /* FEATURE_XARGS_SUPPORT_TERMOPT */
+#endif
 
-                /* allocate pointers for execvp:
-                   argc*arg, n*arg from stdin, NULL */
-                args = xzalloc((n + argc + 1) * sizeof(char *));
+                /* allocate pointers for execvp */
+                args = xzalloc(sizeof(args[0]) * (argc + n + 1));
 
                 /* store the command to be executed
-                   (taken from the command line) */
-                for (i = 0; i < argc; i++)
+                 * (taken from the command line) */
+                for (i = 0; argv[i]; i++)
                         args[i] = argv[i];
                 /* (taken from stdin) */
                 for (cur = list; n; cur = cur->link) {
@@ -535,6 +525,7 @@ int xargs_main(int argc, char **argv)
                         if (!(opt & OPT_INTERACTIVE))
                                 bb_putchar_stderr('\n');
                 }
+
                 if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
                         child_error = xargs_exec(args);
                 }
@@ -546,12 +537,15 @@ int xargs_main(int argc, char **argv)
                         free(cur);
                 }
                 free(args);
+
                 if (child_error > 0 && child_error != 123) {
                         break;
                 }
         } /* while */
+
         if (ENABLE_FEATURE_CLEAN_UP)
-                free(max_chars);
+                free(buf);
+
         return child_error;
 }
 
diff --git a/testsuite/xargs.tests b/testsuite/xargs.tests
index 17f4e7a1b..c73363038 100755
--- a/testsuite/xargs.tests
+++ b/testsuite/xargs.tests
@@ -26,4 +26,9 @@ testing "xargs does not stop on underscore ('new' GNU behavior)" \
         "a _ b\n" \
         "" "a\n_\nb\n"
 
+testing "xargs -s7 can take one-char input" \
+        "xargs -s7" \
+        "a\n" \
+        "" "a\n"
+
 exit $FAILCOUNT