diff options
| -rw-r--r-- | simpletail.c | 55 |
1 files changed, 37 insertions, 18 deletions
diff --git a/simpletail.c b/simpletail.c index b5df235..83541eb 100644 --- a/simpletail.c +++ b/simpletail.c @@ -18,7 +18,13 @@ #define BUFFER_SIZE 4096 -off_t lines(int fd, int file_size, unsigned int nr_lines) +void usage(void) +{ + fprintf(stderr, "usage: simpletail [-f] [-n <nr-lines>] <file>\n"); + exit(EXIT_FAILURE); +} + +off_t lines(int fd, int file_size, unsigned int n_lines) { int i; char buf[BUFFER_SIZE]; @@ -28,7 +34,7 @@ off_t lines(int fd, int file_size, unsigned int nr_lines) if (offset < 0) offset = 0; - while (offset > 0 && nr_lines > 0) { + while (offset > 0 && n_lines > 0) { int rc; int block_size = BUFFER_SIZE; /* Size of the current block we're reading */ @@ -47,15 +53,15 @@ off_t lines(int fd, int file_size, unsigned int nr_lines) for (i = block_size; i > 0; i--) { if (buf[i] == '\n') { dprintf(" Found \\n at position %d\n", i); - nr_lines--; + n_lines--; - if (nr_lines == 0) + if (n_lines == 0) break; } } } - if (nr_lines == 0) + if (n_lines == 0) offset += i + 1; /* We don't want the first \n */ return offset; @@ -136,20 +142,33 @@ int watch_file(const char *filename, off_t offset) int main(int argc, char **argv) { - int fd; - int nr_lines = 0; + int i, fd; + int n_lines = 0; int ret = 0; + short forever = 0; + char buf[BUFFER_SIZE], *filename; struct stat finfo; - char buf[BUFFER_SIZE]; off_t offset = 0; - if (argc < 3) { - fprintf(stderr, "%s <nr-lines> <file> <forever?>\n", argv[0]); - return -1; - } - - nr_lines = strtol(argv[1], NULL, 0) + 1; - fd = open(argv[2], O_RDONLY); + if (argc < 3) + usage(); + + for (i = 1; (i + 1 < argc) && (argv[i][0] == '-'); i++) { + switch (argv[i][1]) { + case 'f': + forever = 1; + break; + case 'n': + n_lines = strtol(argv[++i], NULL, 0) + 1; + break; + default: + usage(); + break; + } + } + + filename = argv[i]; + fd = open(filename, O_RDONLY); if (fd < 0) { perror("open()"); @@ -161,7 +180,7 @@ int main(int argc, char **argv) return -1; } - offset = lines(fd, finfo.st_size, nr_lines); + offset = lines(fd, finfo.st_size, n_lines); dprintf(" offset: %lu.\n", offset); lseek(fd, offset, SEEK_SET); @@ -171,8 +190,8 @@ int main(int argc, char **argv) close(fd); - if (argv[3]) - ret = watch_file(argv[2], finfo.st_size); + if (forever) + ret = watch_file(filename, finfo.st_size); return ret; } |