diff options
author | Jim Meyering <jim@meyering.net> | 2001-11-19 10:59:56 +0000 |
---|---|---|
committer | Jim Meyering <jim@meyering.net> | 2001-11-19 10:59:56 +0000 |
commit | a71d24334e651f4bb8347a6bf4d836bcebf9633d (patch) | |
tree | dbcacac61a5292ef91067644b13079f7ac567969 /src | |
parent | 0ea919d2da14f6c9a36dc1ee155fb528ac223e56 (diff) | |
download | coreutils-a71d24334e651f4bb8347a6bf4d836bcebf9633d.tar.xz |
(xlseek): New function.
Call it instead of lseek, in most cases, so any failure is reported.
Diffstat (limited to 'src')
-rw-r--r-- | src/tail.c | 65 |
1 files changed, 49 insertions, 16 deletions
diff --git a/src/tail.c b/src/tail.c index b358295c3..5bb6ad998 100644 --- a/src/tail.c +++ b/src/tail.c @@ -35,6 +35,7 @@ #include "closeout.h" #include "argmatch.h" #include "error.h" +#include "human.h" #include "safe-read.h" #include "xstrtol.h" @@ -374,6 +375,45 @@ dump_remainder (const char *pretty_filename, int fd, off_t n_bytes) return n_written; } +/* Call lseek with the specified arguments, where file descriptor FD + corresponds to the file, FILENAME. + Give a diagnostic and exit nonzero if lseek fails. */ + +static void +xlseek (int fd, off_t offset, int whence, char const *filename) +{ + off_t new_offset = lseek (fd, offset, whence); + char buf[LONGEST_HUMAN_READABLE + 1]; + char *s; + char const *sign; + + if (0 <= new_offset) + return; + + sign = offset < 0 ? "-" : ""; + if (offset < 0) + offset = -offset; + + s = human_readable ((uintmax_t) offset, buf, 1, 1); + switch (whence) + { + case SEEK_SET: + error (1, errno, _("%s: cannot seek to offset %s%s"), + filename, sign, s); + break; + case SEEK_CUR: + error (1, errno, _("%s: cannot seek to relative offset %s%s"), + filename, sign, s); + break; + case SEEK_END: + error (1, errno, _("%s: cannot seek to end-relative offset %s%s"), + filename, sign, s); + break; + default: + abort (); + } +} + /* Print the last N_LINES lines from the end of file FD. Go backward through the file, reading `BUFSIZ' bytes at a time (except probably the first), until we hit the start of the file or have @@ -403,8 +443,7 @@ file_lines (const char *pretty_filename, int fd, long int n_lines, /* Make `pos' a multiple of `BUFSIZ' (0 if the file is short), so that all reads will be on block boundaries, which might increase efficiency. */ pos -= bytes_read; - /* FIXME: check lseek return value */ - lseek (fd, pos, SEEK_SET); + xlseek (fd, pos, SEEK_SET, pretty_filename); bytes_read = safe_read (fd, buffer, bytes_read); if (bytes_read == -1) { @@ -438,14 +477,12 @@ file_lines (const char *pretty_filename, int fd, long int n_lines, if (pos == start_pos) { /* Not enough lines in the file; print the entire file. */ - /* FIXME: check lseek return value */ - lseek (fd, start_pos, SEEK_SET); + xlseek (fd, start_pos, SEEK_SET, pretty_filename); dump_remainder (pretty_filename, fd, file_length); return 0; } pos -= BUFSIZ; - /* FIXME: check lseek return value */ - lseek (fd, pos, SEEK_SET); + xlseek (fd, pos, SEEK_SET, pretty_filename); } while ((bytes_read = safe_read (fd, buffer, BUFSIZ)) > 0); @@ -850,8 +887,7 @@ recheck (struct File_spec *f) f->n_unchanged_stats = 0; f->n_consecutive_size_changes = 0; f->ignore = 0; - /* FIXME: check lseek return value */ - lseek (f->fd, f->size, SEEK_SET); + xlseek (f->fd, f->size, SEEK_SET, pretty_name (f)); } } @@ -951,8 +987,8 @@ tail_forever (struct File_spec *f, int nfiles) { error (0, 0, _("%s: file truncated"), pretty_name (&f[i])); last = i; - /* FIXME: check lseek return value */ - lseek (f[i].fd, (off_t) stats.st_size, SEEK_SET); + xlseek (f[i].fd, (off_t) stats.st_size, SEEK_SET, + pretty_name (&f[i])); f[i].size = stats.st_size; continue; } @@ -1014,8 +1050,7 @@ tail_bytes (const char *pretty_filename, int fd, off_t n_bytes) { if (S_ISREG (stats.st_mode)) { - /* FIXME: check lseek return value */ - lseek (fd, n_bytes, SEEK_CUR); + xlseek (fd, n_bytes, SEEK_CUR, pretty_filename); } else if (start_bytes (pretty_filename, fd, n_bytes)) { @@ -1050,15 +1085,13 @@ tail_bytes (const char *pretty_filename, int fd, off_t n_bytes) more bytes than have been requested. So reposition the file pointer to the incoming current position and print everything after that. */ - /* FIXME: check lseek return value */ - lseek (fd, current_pos, SEEK_SET); + xlseek (fd, current_pos, SEEK_SET, pretty_filename); } else { /* There are more bytes remaining than were requested. Back up. */ - /* FIXME: check lseek return value */ - lseek (fd, -n_bytes, SEEK_END); + xlseek (fd, -n_bytes, SEEK_END, pretty_filename); } dump_remainder (pretty_filename, fd, n_bytes); } |