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authorTobias Klauser <tklauser@distanz.ch>2006-10-26 20:31:43 +0200
committerTobias Klauser <tklauser@xenon.tklauser.home>2006-10-26 20:31:43 +0200
commitee9871f1934910cd8e88f10d5958afdbf3f0b5ac (patch)
tree3e63e3b9e6f4eb1416aaf324aabfacdab33b67d1
parentf09e7bf71c2b64df952650623fcd0b870c596ca4 (diff)
inotail.c: Support inotail -n +<num>
Add function lines_to_offset_from_begin() to allow tailing relative to the begin of the file. Also handle the case where the argument for '-c' or 'n' is '+0'. Like GNU tail (and according to its source also tail in UNIX) print the whole file in this case.
-rw-r--r--inotail.c55
1 files changed, 51 insertions, 4 deletions
diff --git a/inotail.c b/inotail.c
index ded9e43..9356158 100644
--- a/inotail.c
+++ b/inotail.c
@@ -96,15 +96,58 @@ static void write_header(char *filename)
first_file = 0;
}
+static off_t lines_to_offset_from_begin(struct file_struct *f, unsigned int n_lines)
+{
+ char buf[BUFFER_SIZE];
+ off_t offset = 0;
+
+ /* tail everything vor 'inotail -n +0' */
+ if (n_lines == 0)
+ return 0;
+
+ memset(&buf, 0, sizeof(buf));
+
+ n_lines--;
+
+ while (offset <= f->st_size && n_lines > 0) {
+ int i, rc;
+ int block_size = BUFFER_SIZE;
+
+ lseek(f->fd, offset, SEEK_SET);
+
+ rc = read(f->fd, &buf, block_size);
+ if (rc < 0) {
+ fprintf(stderr, "Error: Could not read from file '%s' (%s)\n", f->name, strerror(errno));
+ return -1;
+ }
+
+ for (i = 0; i < block_size; i++) {
+ if (buf[i] == '\n') {
+ n_lines--;
+ if (n_lines == 0) {
+ offset += i + 1;
+ return offset;
+ }
+ }
+ }
+
+ offset += block_size;
+ }
+
+ return offset;
+}
+
static off_t lines_to_offset(struct file_struct *f, unsigned int n_lines)
{
char buf[BUFFER_SIZE];
off_t offset = f->st_size;
- memset(&buf, 0, sizeof(buf));
+ if (from_begin)
+ return lines_to_offset_from_begin(f, n_lines);
+ else
+ n_lines++; /* We also count the last \n */
- if (!from_begin)
- n_lines += 1; /* We also count the last \n */
+ memset(&buf, 0, sizeof(buf));
while (offset > 0 && n_lines > 0) {
int i, rc;
@@ -141,7 +184,11 @@ static off_t lines_to_offset(struct file_struct *f, unsigned int n_lines)
static inline off_t bytes_to_offset(struct file_struct *f, unsigned int n_bytes)
{
- return from_begin ? ((off_t) n_bytes - 1) : (f->st_size - n_bytes);
+ /* tail everything vor 'inotail -c +0' */
+ if (from_begin && n_bytes == 0)
+ return 0;
+ else
+ return (from_begin ? ((off_t) n_bytes - 1) : (f->st_size - (off_t) n_bytes));
}
static int tail_pipe(struct file_struct *f)