a43df64ee
Denys Vlasenko
2009-08-09
Subject
tail: fix "tail +N file_shorter_than_N"
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coreutils/tail.c+10 -6
| @@ -50,12 +50,12 @@ static ssize_t tail_read(int fd, char *buf, size_t count) | |
| off_t current; | |
| struct stat sbuf; | |
| - | /* (A good comment is missing here) */ |
| - | current = lseek(fd, 0, SEEK_CUR); |
| /* /proc files report zero st_size, don't lseek them. */ | |
| - | if (fstat(fd, &sbuf) == 0 && sbuf.st_size) |
| + | if (fstat(fd, &sbuf) == 0 && sbuf.st_size) { |
| + | current = lseek(fd, 0, SEEK_CUR); |
| if (sbuf.st_size < current) | |
| lseek(fd, 0, SEEK_SET); | |
| + | } |
| r = full_read(fd, buf, count); | |
| if (r < 0) { | |
| @@ -119,10 +119,11 @@ int tail_main(int argc, char **argv) | |
| #if ENABLE_FEATURE_FANCY_TAIL | |
| /* q: make it impossible for nfiles to be > header_threshhold */ | |
| if (opt & 0x8) header_threshhold = UINT_MAX; // -q | |
| + | //if (opt & 0x10) // -s |
| if (opt & 0x20) header_threshhold = 0; // -v | |
| - | #define FOLLOW_RETRY (opt & 0x40) |
| + | # define FOLLOW_RETRY (opt & 0x40) |
| #else | |
| - | #define FOLLOW_RETRY 0 |
| + | # define FOLLOW_RETRY 0 |
| #endif | |
| argc -= optind; | |
| argv += optind; | |
| @@ -189,7 +190,7 @@ int tail_main(int argc, char **argv) | |
| off_t current = lseek(fds[i], 0, SEEK_END); | |
| if (current > 0) { | |
| if (count == 0) | |
| - | continue; /* showing zero lines is easy :) */ |
| + | continue; /* showing zero bytes is easy :) */ |
| current -= count; | |
| if (current < 0) | |
| current = 0; | |
| @@ -201,12 +202,15 @@ int tail_main(int argc, char **argv) | |
| buf = tailbuf; | |
| taillen = 0; | |
| + | /* "We saw 1st line/byte". |
| + | * Used only by +N code ("start from Nth", 1-based) */ |
| seen = 1; | |
| newlines_seen = 0; | |
| while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) { | |
| if (from_top) { | |
| int nwrite = nread; | |
| if (seen < count) { | |
| + | /* We need to skip a few more bytes/lines */ |
| if (COUNT_BYTES) { | |
| nwrite -= (count - seen); | |
| seen = count; | |
testsuite/tail.tests+17 -0
| @@ -0,0 +1,17 @@ | |
| + | #!/bin/sh |
| + | |
| + | # Copyright 2009 by Denys Vlasenko <[email protected]> |
| + | # Licensed under GPL v2, see file LICENSE for details. |
| + | |
| + | . testing.sh |
| + | |
| + | # testing "test name" "command" "expected result" "file input" "stdin" |
| + | # file input will be file called "input" |
| + | # test can create a file "actual" instead of writing to stdout |
| + | |
| + | testing "tail: +N with N > file length" \ |
| + | "tail -c +55 2>&1; echo \$?" \ |
| + | "0\n" \ |
| + | "" "qw" |
| + | |
| + | exit $FAILCOUNT |