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authorTobias Klauser <tklauser@distanz.ch>2006-08-26 20:30:58 +0200
committerTobias Klauser <tklauser@xenon.tklauser.home>2006-08-26 20:30:58 +0200
commite9cea9de2b1ec6368c6fb4f205022028e5ef7119 (patch)
tree21ecd6b29447ecb2bb1a76ce16eca4d1151b9fcc /inotail.c
parentae595b24bf3043013ce0c4001929be90d5d1abae (diff)
Better error handling and preparation for tail from stdin
Diffstat (limited to 'inotail.c')
-rw-r--r--inotail.c59
1 files changed, 46 insertions, 13 deletions
diff --git a/inotail.c b/inotail.c
index e5ecf89..88271f5 100644
--- a/inotail.c
+++ b/inotail.c
@@ -110,8 +110,7 @@ static off_t lines_to_offset(struct file_struct *f, unsigned int n_lines)
n_lines--;
if (n_lines == 0) {
- /* We don't want the first \n */
- offset += i + 1;
+ offset += i + 1; /* We don't want the first \n */
break;
}
}
@@ -121,6 +120,20 @@ static off_t lines_to_offset(struct file_struct *f, unsigned int n_lines)
return offset;
}
+static int bytes_to_offset(struct file_struct *f, int n_lines)
+{
+ int ret = f->st_size - n_lines;
+
+ return (ret < 0 ? 0 : ret);
+}
+
+/* We will just tail everything here */
+static int tail_pipe(struct file_struct *f)
+{
+ dprintf(" Trying to tail from '%s'\n", f->name);
+ return 0;
+}
+
static int tail_file(struct file_struct *f, int n_lines, char mode)
{
ssize_t rc = 0;
@@ -128,10 +141,14 @@ static int tail_file(struct file_struct *f, int n_lines, char mode)
char buf[BUFFER_SIZE];
struct stat finfo;
- f->fd = open(f->name, O_RDONLY);
- if (f->fd < 0) {
- fprintf(stderr, "Error: Could not open file '%s' (%s)\n", f->name, strerror(errno));
- return -1;
+ if (strncmp(f->name, "-", 1) == 0)
+ f->fd = STDIN_FILENO;
+ else {
+ f->fd = open(f->name, O_RDONLY);
+ if (f->fd < 0) {
+ fprintf(stderr, "Error: Could not open file '%s' (%s)\n", f->name, strerror(errno));
+ return -1;
+ }
}
if (fstat(f->fd, &finfo) < 0) {
@@ -140,13 +157,18 @@ static int tail_file(struct file_struct *f, int n_lines, char mode)
return -1;
}
+ /* We cannot seek on these */
+ if (!S_ISREG(finfo.st_mode) || f->fd == STDIN_FILENO)
+ return tail_pipe(f);
+
f->st_size = finfo.st_size;
if (mode == M_LINES)
offset = lines_to_offset(f, n_lines);
- else /* Bytewise tail */
- offset = f->st_size - n_lines;
+ else /* Bytewise tail, n_lines is number of bytes here */
+ offset = bytes_to_offset(f, n_lines);
+ /* We only get negative offsets on errors */
if (offset < 0)
return -1;
@@ -155,13 +177,14 @@ static int tail_file(struct file_struct *f, int n_lines, char mode)
lseek(f->fd, offset, SEEK_SET);
- while ((rc = read(f->fd, &buf, BUFFER_SIZE)) != 0) {
+ while ((rc = read(f->fd, &buf, BUFFER_SIZE)) > 0) {
dprintf(" f->st_size - offset: %lu\n", f->st_size - offset);
dprintf(" rc: %d\n", rc);
write(STDOUT_FILENO, buf, (size_t) rc);
}
- close(f->fd);
+ if (close(f->fd) < 0)
+ fprintf(stderr, "Error: Could not close file '%s' (%s)\n", f->name, strerror(errno));
return 0;
}
@@ -321,9 +344,19 @@ int main(int argc, char **argv)
n_files = argc - opt;
filenames = argv + opt;
} else {
- /* For now, reading from stdin will be implemented later (tm) */
- /* XXX: This is not like GNU tail behaves! */
- usage(EXIT_FAILURE);
+ /* It must be stdin then */
+ static char *dummy_stdin = "-";
+ n_files++;
+ filenames = &dummy_stdin;
+
+ /* POSIX says that -f is ignored if no file operand is
+ specified and standard input is a pipe. */
+ if (forever) {
+ struct stat finfo;
+ if (fstat(STDIN_FILENO, &finfo) == 0
+ && (S_ISFIFO(finfo.st_mode) || S_ISSOCK(finfo.st_mode)))
+ forever = 0;
+ }
}
files = malloc(n_files * sizeof(struct file_struct));