diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/lib.c | 31 |
1 files changed, 19 insertions, 12 deletions
@@ -89,24 +89,31 @@ ssize_t writeall(int fd, void *buf, size_t len) return count; } +// skip this many bytes of input. Return 0 for success, >0 means this much +// left after input skipped. off_t lskip(int fd, off_t offset) { - off_t and = lseek(fd, offset, SEEK_CUR); + off_t cur = lseek(fd, 0, SEEK_CUR); - if (and != -1 && offset >= lseek(fd, offset, SEEK_END) - && offset+and == lseek(fd, offset+and, SEEK_SET)) return 0; - else { - while (offset>0) { - int try = offset>sizeof(libbuf) ? sizeof(libbuf) : offset, or; + if (cur != -1) { + off_t end = lseek(fd, 0, SEEK_END) - cur; - or = readall(fd, libbuf, try); - if (or < 0) perror_msg("lskip to %lld", (long long)offset); - else offset -= try; - if (or < try) break; - } + if (end > 0 && end < offset) return offset - end; + end = offset+cur; + if (end == lseek(fd, end, SEEK_SET)) return 0; + perror_exit("lseek"); + } - return offset; + while (offset>0) { + int try = offset>sizeof(libbuf) ? sizeof(libbuf) : offset, or; + + or = readall(fd, libbuf, try); + if (or < 0) perror_exit("lskip to %lld", (long long)offset); + else offset -= try; + if (or < try) break; } + + return offset; } // Split a path into linked list of components, tracking head and tail of list. |