tail: -50 text bytes

1 files changed, 48 insertions, 88 deletions

diff --git a/coreutils/tail.c b/coreutils/tail.c
index b690b370e..a753a10b7 100644
--- a/coreutils/tail.c
+++ b/coreutils/tail.c
@@ -29,44 +29,30 @@
 static const struct suffix_mult tail_suffixes[] = {
         { "b", 512 },
         { "k", 1024 },
-        { "m", 1048576 },
+        { "m", 1024*1024 },
         { NULL, 0 }
 };
 
 static int status;
 
-static void tail_xbb_full_write(const char *buf, size_t len)
-{
-        /* If we get a write error, there is really no sense in continuing. */
-        if (full_write(STDOUT_FILENO, buf, len) < 0)
-                bb_perror_nomsg_and_die();
-}
-
 static void tail_xprint_header(const char *fmt, const char *filename)
 {
-#if defined __GLIBC__
-        if (dprintf(STDOUT_FILENO, fmt, filename) < 0) {
+        if (fdprintf(STDOUT_FILENO, fmt, filename) < 0)
                 bb_perror_nomsg_and_die();
-        }
-#else
-        int hdr_len = strlen(fmt) + strlen(filename);
-        char *hdr = xzalloc(hdr_len);
-        sprintf(hdr, filename, filename);
-        tail_xbb_full_write(hdr, hdr_len);
-#endif
 }
 
 static ssize_t tail_read(int fd, char *buf, size_t count)
 {
         ssize_t r;
-        off_t current,end;
+        off_t current, end;
         struct stat sbuf;
 
         end = current = lseek(fd, 0, SEEK_CUR);
         if (!fstat(fd, &sbuf))
                 end = sbuf.st_size;
         lseek(fd, end < current ? 0 : current, SEEK_SET);
-        if ((r = safe_read(fd, buf, count)) < 0) {
+        r = safe_read(fd, buf, count);
+        if (r < 0) {
                 bb_perror_msg(bb_msg_read_error);
                 status = EXIT_FAILURE;
         }
@@ -74,82 +60,55 @@ static ssize_t tail_read(int fd, char *buf, size_t count)
         return r;
 }
 
-static const char tail_opts[] =
-        "fn:c:"
-#if ENABLE_FEATURE_FANCY_TAIL
-        "qs:v"
-#endif
-        ;
-
 static const char header_fmt[] = "\n==> %s <==\n";
 
 int tail_main(int argc, char **argv)
 {
-        long count = 10;
+        unsigned count = 10;
         unsigned sleep_period = 1;
         int from_top = 0;
-        int follow = 0;
         int header_threshhold = 1;
-        int count_bytes = 0;
+        const char *str_c, *str_n, *str_s;
 
         char *tailbuf;
         size_t tailbufsize;
         int taillen = 0;
         int newline = 0;
+        int nfiles, nread, nwrite, seen, i, opt;
 
-        int *fds, nfiles, nread, nwrite, seen, i, opt;
+        int *fds;
         char *s, *buf;
         const char *fmt;
 
+        void eat_num(const char *p) {
+                if (*p == '-') p++;
+                else if (*p == '+') { p++; from_top = 1; }
+                count = xatou_sfx(p, tail_suffixes);
+        }
+
+
 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
         /* Allow legacy syntax of an initial numeric option without -n. */
         if (argc >= 2 && (argv[1][0] == '+' || argv[1][0] == '-')
          && isdigit(argv[1][1])
         ) {
-                optind = 2;
-                optarg = argv[1];
-                goto GET_COUNT;
+                argv[0] = "-n";
+                argv--;
+                argc++;
         }
 #endif
 
-        while ((opt = getopt(argc, argv, tail_opts)) > 0) {
-                switch (opt) {
-                        case 'f':
-                                follow = 1;
-                                break;
-                        case 'c':
-                                count_bytes = 1;
-                                /* FALLS THROUGH */
-                        case 'n':
-#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
- GET_COUNT:
-#endif
-                                from_top = 0;
-                                if (*optarg == '+') {
-                                        ++optarg;
-                                        from_top = 1;
-                                }
-                                count = xatol_sfx(optarg, tail_suffixes);
-                                /* Note: Leading whitespace is an error trapped above. */
-                                if (count < 0) {
-                                        count = -count;
-                                }
-                                break;
+        opt = getopt32(argc, argv, "fc:n:" USE_FEATURE_FANCY_TAIL("qs:v"), &str_c, &str_n, &str_s);
+#define FOLLOW (opt & 0x1)
+#define COUNT_BYTES (opt & 0x2)
+        //if (opt & 0x1) // -f
+        if (opt & 0x2) eat_num(str_c); // -c
+        if (opt & 0x4) eat_num(str_n); // -n
 #if ENABLE_FEATURE_FANCY_TAIL
-                        case 'q':
-                                header_threshhold = INT_MAX;
-                                break;
-                        case 's':
-                                sleep_period = xatou(optarg);
-                                break;
-                        case 'v':
-                                header_threshhold = 0;
-                                break;
+        if (opt & 0x8) header_threshhold = INT_MAX; // -q
+        if (opt & 0x10) sleep_period = xatou(str_s); // -s
+        if (opt & 0x20) header_threshhold = 0; // -v
 #endif
-                        default:
-                                bb_show_usage();
-                }
-        }
         argc -= optind;
         argv += optind;
 
@@ -160,34 +119,35 @@ int tail_main(int argc, char **argv)
                 struct stat statbuf;
 
                 if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) {
-                        follow = 0;
+                        opt &= ~1; /* clear FOLLOW */
                 }
                 *argv = (char *) bb_msg_standard_input;
                 goto DO_STDIN;
         }
 
         do {
-                if (LONE_DASH(argv[i])) {
- DO_STDIN:
+                if (NOT_LONE_DASH(argv[i])) {
+                        fds[nfiles] = open(argv[i], O_RDONLY);
+                        if (fds[nfiles] < 0) {
+                                bb_perror_msg("%s", argv[i]);
+                                status = EXIT_FAILURE;
+                                continue;
+                        }
+                } else {
+ DO_STDIN:              /* "-" */
                         fds[nfiles] = STDIN_FILENO;
-                } else if ((fds[nfiles] = open(argv[i], O_RDONLY)) < 0) {
-                        bb_perror_msg("%s", argv[i]);
-                        status = EXIT_FAILURE;
-                        continue;
                 }
                 argv[nfiles] = argv[i];
                 ++nfiles;
         } while (++i < argc);
 
-        if (!nfiles) {
+        if (!nfiles)
                 bb_error_msg_and_die("no files");
-        }
 
         tailbufsize = BUFSIZ;
 
         /* tail the files */
-        if (from_top < count_bytes) {   /* Each is 0 or 1, so true iff 0 < 1. */
-                /* Hence, !from_top && count_bytes */
+        if (!from_top && COUNT_BYTES) {
                 if (tailbufsize < count) {
                         tailbufsize = count + BUFSIZ;
                 }
@@ -203,7 +163,7 @@ int tail_main(int argc, char **argv)
                  * starting file position may not be the beginning of the file.
                  * Beware of backing up too far.  See example in wc.c.
                  */
-                if ((!(count|from_top)) && (lseek(fds[i], 0, SEEK_END) >= 0)) {
+                if (!(count|from_top) && lseek(fds[i], 0, SEEK_END) >= 0) {
                         continue;
                 }
 
@@ -221,22 +181,22 @@ int tail_main(int argc, char **argv)
                         if (from_top) {
                                 nwrite = nread;
                                 if (seen < count) {
-                                        if (count_bytes) {
+                                        if (COUNT_BYTES) {
                                                 nwrite -= (count - seen);
                                                 seen = count;
                                         } else {
                                                 s = buf;
                                                 do {
                                                         --nwrite;
-                                                        if ((*s++ == '\n') && (++seen == count)) {
+                                                        if (*s++ == '\n' && ++seen == count) {
                                                                 break;
                                                         }
                                                 } while (nwrite);
                                         }
                                 }
-                                tail_xbb_full_write(buf + nread - nwrite, nwrite);
+                                xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
                         } else if (count) {
-                                if (count_bytes) {
+                                if (COUNT_BYTES) {
                                         taillen += nread;
                                         if (taillen > count) {
                                                 memmove(tailbuf, tailbuf + taillen - count, count);
@@ -286,7 +246,7 @@ int tail_main(int argc, char **argv)
                 }
 
                 if (!from_top) {
-                        tail_xbb_full_write(tailbuf, taillen);
+                        xwrite(STDOUT_FILENO, tailbuf, taillen);
                 }
 
                 taillen = 0;
@@ -296,7 +256,7 @@ int tail_main(int argc, char **argv)
 
         fmt = NULL;
 
-        while (follow) {
+        if (FOLLOW) while (1) {
                 sleep(sleep_period);
                 i = 0;
                 do {
@@ -308,7 +268,7 @@ int tail_main(int argc, char **argv)
                                         tail_xprint_header(fmt, argv[i]);
                                         fmt = NULL;
                                 }
-                                tail_xbb_full_write(buf, nread);
+                                xwrite(STDOUT_FILENO, buf, nread);
                         }
                 } while (++i < nfiles);
         }