3b5a66444
Eric Lammerts
2009-07-22
Subject
tail: implement -F
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Commit Diff GitHub →
coreutils/Config.in+1 -1
| @@ -635,7 +635,7 @@ config TAIL | |
| from files. | |
| config FEATURE_FANCY_TAIL | |
| - | bool "Enable extra tail options (-q, -s, and -v)" |
| + | bool "Enable extra tail options (-q, -s, -v, and -F)" |
| default y | |
| depends on TAIL | |
| help | |
coreutils/tail.c+65 -20
| @@ -85,18 +85,15 @@ int tail_main(int argc, char **argv) | |
| unsigned count = 10; | |
| unsigned sleep_period = 1; | |
| bool from_top; | |
| - | int header_threshhold = 1; |
| const char *str_c, *str_n; | |
| char *tailbuf; | |
| size_t tailbufsize; | |
| - | int taillen = 0; |
| - | int newlines_seen = 0; |
| - | int nfiles, nread, nwrite, i, opt; |
| - | unsigned seen; |
| + | unsigned header_threshhold = 1; |
| + | unsigned nfiles; |
| + | int i, opt; |
| int *fds; | |
| - | char *s, *buf; |
| const char *fmt; | |
| #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL | |
| @@ -110,8 +107,9 @@ int tail_main(int argc, char **argv) | |
| } | |
| #endif | |
| - | IF_FEATURE_FANCY_TAIL(opt_complementary = "s+";) /* -s N */ |
| - | opt = getopt32(argv, "fc:n:" IF_FEATURE_FANCY_TAIL("qs:v"), |
| + | /* -s NUM, -F imlies -f */ |
| + | IF_FEATURE_FANCY_TAIL(opt_complementary = "s+:Ff";) |
| + | opt = getopt32(argv, "fc:n:" IF_FEATURE_FANCY_TAIL("qs:vF"), |
| &str_c, &str_n IF_FEATURE_FANCY_TAIL(,&sleep_period)); | |
| #define FOLLOW (opt & 0x1) | |
| #define COUNT_BYTES (opt & 0x2) | |
| @@ -119,8 +117,12 @@ int tail_main(int argc, char **argv) | |
| if (opt & 0x2) count = eat_num(str_c); // -c | |
| if (opt & 0x4) count = eat_num(str_n); // -n | |
| #if ENABLE_FEATURE_FANCY_TAIL | |
| - | if (opt & 0x8) header_threshhold = INT_MAX; // -q |
| + | /* q: make it impossible for nfiles to be > header_threshhold */ |
| + | if (opt & 0x8) header_threshhold = UINT_MAX; // -q |
| if (opt & 0x20) header_threshhold = 0; // -v | |
| + | #define FOLLOW_RETRY (opt & 0x40) |
| + | #else |
| + | #define FOLLOW_RETRY 0 |
| #endif | |
| argc -= optind; | |
| argv += optind; | |
| @@ -128,19 +130,21 @@ int tail_main(int argc, char **argv) | |
| G.status = EXIT_SUCCESS; | |
| /* open all the files */ | |
| - | fds = xmalloc(sizeof(int) * (argc + 1)); |
| + | fds = xmalloc(sizeof(fds[0]) * (argc + 1)); |
| if (!argv[0]) { | |
| struct stat statbuf; | |
| - | if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) { |
| + | if (fstat(STDIN_FILENO, &statbuf) == 0 |
| + | && S_ISFIFO(statbuf.st_mode) |
| + | ) { |
| opt &= ~1; /* clear FOLLOW */ | |
| } | |
| - | *argv = (char *) bb_msg_standard_input; |
| + | argv[0] = (char *) bb_msg_standard_input; |
| } | |
| nfiles = i = 0; | |
| do { | |
| int fd = open_or_warn_stdin(argv[i]); | |
| - | if (fd < 0) { |
| + | if (fd < 0 && !FOLLOW_RETRY) { |
| G.status = EXIT_FAILURE; | |
| continue; | |
| } | |
| @@ -161,9 +165,18 @@ int tail_main(int argc, char **argv) | |
| tailbuf = xmalloc(tailbufsize); | |
| /* tail the files */ | |
| - | fmt = header_fmt + 1; /* Skip header leading newline on first output. */ |
| + | fmt = header_fmt + 1; /* skip header leading newline on first output */ |
| i = 0; | |
| do { | |
| + | char *buf; |
| + | int taillen; |
| + | int newlines_seen; |
| + | unsigned seen; |
| + | int nread; |
| + | |
| + | if (ENABLE_FEATURE_FANCY_TAIL && fds[i] < 0) |
| + | continue; /* may happen with -E */ |
| + | |
| if (nfiles > header_threshhold) { | |
| tail_xprint_header(fmt, argv[i]); | |
| fmt = header_fmt; | |
| @@ -192,13 +205,13 @@ int tail_main(int argc, char **argv) | |
| newlines_seen = 0; | |
| while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) { | |
| if (from_top) { | |
| - | nwrite = nread; |
| + | int nwrite = nread; |
| if (seen < count) { | |
| if (COUNT_BYTES) { | |
| nwrite -= (count - seen); | |
| seen = count; | |
| } else { | |
| - | s = buf; |
| + | char *s = buf; |
| do { | |
| --nwrite; | |
| if (*s++ == '\n' && ++seen == count) { | |
| @@ -231,6 +244,7 @@ int tail_main(int argc, char **argv) | |
| taillen += nread; | |
| } else { | |
| int extra = (buf[nread-1] != '\n'); | |
| + | char *s; |
| k = newlines_seen + newlines_in_buf + extra - count; | |
| s = tailbuf; | |
| @@ -257,23 +271,54 @@ int tail_main(int argc, char **argv) | |
| } | |
| } while (++i < nfiles); | |
| - | buf = xrealloc(tailbuf, BUFSIZ); |
| + | tailbuf = xrealloc(tailbuf, BUFSIZ); |
| fmt = NULL; | |
| if (FOLLOW) while (1) { | |
| sleep(sleep_period); | |
| + | |
| i = 0; | |
| do { | |
| + | int nread; |
| + | const char *filename = argv[i]; |
| + | int fd = fds[i]; |
| + | |
| + | if (FOLLOW_RETRY) { |
| + | struct stat sbuf, fsbuf; |
| + | |
| + | if (fd < 0 |
| + | || fstat(fd, &fsbuf) < 0 |
| + | || stat(filename, &sbuf) < 0 |
| + | || fsbuf.st_dev != sbuf.st_dev |
| + | || fsbuf.st_ino != sbuf.st_ino |
| + | ) { |
| + | int new_fd; |
| + | |
| + | if (fd >= 0) |
| + | close(fd); |
| + | new_fd = open(filename, O_RDONLY); |
| + | if (new_fd >= 0) { |
| + | bb_error_msg("%s has %s; following end of new file", |
| + | filename, (fd < 0) ? "appeared" : "been replaced" |
| + | ); |
| + | } else if (fd >= 0) { |
| + | bb_perror_msg("%s has become inaccessible", filename); |
| + | } |
| + | fds[i] = fd = new_fd; |
| + | } |
| + | } |
| + | if (ENABLE_FEATURE_FANCY_TAIL && fd < 0) |
| + | continue; |
| if (nfiles > header_threshhold) { | |
| fmt = header_fmt; | |
| } | |
| - | while ((nread = tail_read(fds[i], buf, BUFSIZ)) > 0) { |
| + | while ((nread = tail_read(fd, tailbuf, BUFSIZ)) > 0) { |
| if (fmt) { | |
| - | tail_xprint_header(fmt, argv[i]); |
| + | tail_xprint_header(fmt, filename); |
| fmt = NULL; | |
| } | |
| - | xwrite(STDOUT_FILENO, buf, nread); |
| + | xwrite(STDOUT_FILENO, tailbuf, nread); |
| } | |
| } while (++i < nfiles); | |
| } | |