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authorEric Lammerts <busybox@lists.lammerts.org>2009-07-21 22:31:27 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2009-07-21 22:31:27 (GMT)
commit3b5a66444030949027dacf4c372713fe33f1d9d9 (patch)
treecde2fc60c110415d134e232d3a6e4eac810a1bde
parent997538ab586e9b061b33c24f2ddced18a0379826 (diff)
downloadbusybox-3b5a66444030949027dacf4c372713fe33f1d9d9.tar.gz
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tail: implement -F
function old new delta tail_main 1190 1494 +304 Signed-off-by: Eric Lammerts <busybox@lists.lammerts.org> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--coreutils/Config.in2
-rw-r--r--coreutils/tail.c85
2 files changed, 66 insertions, 21 deletions
diff --git a/coreutils/Config.in b/coreutils/Config.in
index 1bc047c..cacfb96 100644
--- a/coreutils/Config.in
+++ b/coreutils/Config.in
@@ -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
diff --git a/coreutils/tail.c b/coreutils/tail.c
index 3ce6be0..ef1326c 100644
--- a/coreutils/tail.c
+++ b/coreutils/tail.c
@@ -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);
}