DeforaOS/utils
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Implemented tail -f

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This commit is contained in:
Pierre Pronchery 2011-07-05 01:17:28 +00:00
parent fdeaf6a651
commit 85badc1dcf
1 changed files with 45 additions and 0 deletions
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45
src/tail.c
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@ -15,6 +15,7 @@
#include <sys/stat.h>
#include <unistd.h> #include <unistd.h>
#include <stdlib.h> #include <stdlib.h>
#include <stdio.h> #include <stdio.h>
@ -35,6 +36,7 @@ typedef struct _Prefs
static int _tail_error(char const * message, int ret); static int _tail_error(char const * message, int ret);
static int _tail_do_bytes(Prefs * prefs, FILE * fp, char const * filename); static int _tail_do_bytes(Prefs * prefs, FILE * fp, char const * filename);
static int _tail_do_lines(Prefs * prefs, FILE * fp, char const * filename); static int _tail_do_lines(Prefs * prefs, FILE * fp, char const * filename);
static int _tail_wait(FILE * fp, char const * filename);
static int _tail(Prefs * prefs, char const * filename) static int _tail(Prefs * prefs, char const * filename)
{ {
@ -49,6 +51,8 @@ static int _tail(Prefs * prefs, char const * filename)
else else
ret = _tail_do_lines(prefs, fp, filename != NULL ret = _tail_do_lines(prefs, fp, filename != NULL
? filename : "stdin"); ? filename : "stdin");
if(prefs->flags & TAIL_PREFS_f)
_tail_wait(fp, filename);
if(filename != NULL && fclose(fp) != 0) if(filename != NULL && fclose(fp) != 0)
return _tail_error(filename, 1); return _tail_error(filename, 1);
return ret; return ret;
@ -155,6 +159,47 @@ static void _lines_print(char ** lines, int pos)
} }
} }
static int _tail_wait(FILE * fp, char const * filename)
{
int fd = fileno(fp);
struct stat st1;
struct stat st2;
off_t seek;
size_t size;
size_t i;
char buf[1024];
ssize_t ssize;
if(fstat(fd, &st1) != 0)
return -_tail_error(filename, 1);
for(;;)
{
sleep(1);
if(fstat(fd, &st2) != 0)
return -_tail_error(filename, 1);
if(st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino)
{
/* XXX this code path is probably impossible */
seek = 0;
size = st2.st_size;
}
else if(st2.st_size > st1.st_size)
{
seek = st1.st_size;
size = st2.st_size - st1.st_size;
}
else
continue;
fseek(fp, seek, SEEK_SET);
for(i = 0; i < size; i+=sizeof(buf))
if((ssize = fread(buf, sizeof(*buf), sizeof(buf), fp))
> 0)
fwrite(buf, sizeof(*buf), ssize, stdout);
st1 = st2;
}
return 0;
}
/* usage */ /* usage */
static int _usage(void) static int _usage(void)