[PATCH 03/33] utmpdump: add option to write to a file

Sami Kerola
2013-04-13T19:55:16Z

bash-completion/utmpdump | 2 +-
login-utils/utmpdump.1 | 4 ++-
login-utils/utmpdump.c | 92 ++++++++++++++++++++++++++++--------------------
3 files changed, 58 insertions(+), 40 deletions(-)

diff --git a/bash-completion/utmpdump b/bash-completion/utmpdump
index 3b868ce..48af5bc 100644
--- a/bash-completion/utmpdump
+++ b/bash-completion/utmpdump
@@ -11,7 +11,7 @@ _utmpdump_module()
esac
case $cur in
-*)
- OPTS="--follow --reverse --version --help"
+ OPTS="--follow --reverse --output --version --help"
COMPREPLY=( $(compgen -W "${OPTS[*]}" -- $cur) )
return 0
;;
diff --git a/login-utils/utmpdump.1 b/login-utils/utmpdump.1
index 35565a4..25f361a 100644
--- a/login-utils/utmpdump.1
+++ b/login-utils/utmpdump.1
@@ -19,7 +19,7 @@
.SH NAME
utmpdump \- dump UTMP and WTMP files in raw format
.SH SYNOPSIS
-utmpdump [\-frh] [ filename ]
+utmpdump [\-frohV] [ filename ]
.SH DESCRIPTION
.B utmpdump
is a simple program to dump UTMP and WTMP files in raw format, so they
@@ -33,6 +33,8 @@ is passed.
Output appended data as the file grows.
.IP "\fB\-r\fR, \fB\-\-reverse\fP
Undump, write back edited login information into utmp or wtmp files.
+.IP "\fB\-o\fR, \fB\-\-output\fP \fIfile\fR
+Write command output to file instead of standard output.
.IP "\fB\-h\fR, \fB\-\-help\fP"
Print a help text and exit.
.IP "\fB\-V\fR, \fB\-\-version\fP"
diff --git a/login-utils/utmpdump.c b/login-utils/utmpdump.c
index b015e1b..af3f7c0 100644
--- a/login-utils/utmpdump.c
+++ b/login-utils/utmpdump.c
@@ -83,7 +83,7 @@ static void xcleanse(char *s, int len)
*s = '?';
}

-static void print_utline(struct utmp ut)
+static void print_utline(struct utmp ut, FILE *out)
{
char *addr_string, *time_string;
struct in_addr in;
@@ -97,7 +97,7 @@ static void print_utline(struct utmp ut)
cleanse(ut.ut_host);

/* pid id user line host addr time */
- printf("[%d] [%05d] [%-4.4s] [%-*.*s] [%-*.*s] [%-*.*s] [%-15.15s] [%-28.28s]\n",
+ fprintf(out, "[%d] [%05d] [%-4.4s] [%-*.*s] [%-*.*s] [%-*.*s] [%-15.15s] [%-28.28s]\n",
ut.ut_type, ut.ut_pid, ut.ut_id, 8, UT_NAMESIZE, ut.ut_user,
12, UT_LINESIZE, ut.ut_line, 20, UT_HOSTSIZE, ut.ut_host,
addr_string, time_string);
@@ -107,28 +107,28 @@ static void print_utline(struct utmp ut)
#define EVENTS (IN_MODIFY|IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT)
#define NEVENTS 4

-static void roll_file(const char *filename, off_t *size)
+static void roll_file(const char *filename, off_t *size, FILE *out)
{
- FILE *fp;
+ FILE *in;
struct stat st;
struct utmp ut;
off_t pos;

- if (!(fp = fopen(filename, "r")))
+ if (!(in = fopen(filename, "r")))
err(EXIT_FAILURE, _("cannot open %s"), filename);

- if (fstat(fileno(fp), &st) == -1)
+ if (fstat(fileno(in), &st) == -1)
err(EXIT_FAILURE, _("%s: stat failed"), filename);

if (st.st_size == *size)
goto done;

- if (fseek(fp, *size, SEEK_SET) != (off_t) -1) {
- while (fread(&ut, sizeof(ut), 1, fp) == 1)
- print_utline(ut);
+ if (fseek(in, *size, SEEK_SET) != (off_t) -1) {
+ while (fread(&ut, sizeof(ut), 1, in) == 1)
+ print_utline(ut, out);
}

- pos = ftello(fp);
+ pos = ftello(in);
/* If we've successfully read something, use the file position, this
* avoids data duplication. If we read nothing or hit an error,
* reset to the reported size, this handles truncated files.
@@ -136,10 +136,10 @@ static void roll_file(const char *filename, off_t *size)
*size = (pos != -1 && pos != *size) ? pos : st.st_size;

done:
- fclose(fp);
+ fclose(in);
}

-static int follow_by_inotify(FILE *fp, const char *filename)
+static int follow_by_inotify(FILE *in, const char *filename, FILE *out)
{
char buf[NEVENTS * sizeof(struct inotify_event)];
int fd, wd, event;
@@ -150,8 +150,8 @@ static int follow_by_inotify(FILE *fp, const char *filename)
if (fd == -1)
return -1; /* probably reached any limit ... */

- size = ftello(fp);
- fclose(fp);
+ size = ftello(in);
+ fclose(in);

wd = inotify_add_watch(fd, filename, EVENTS);
if (wd == -1)
@@ -172,7 +172,7 @@ static int follow_by_inotify(FILE *fp, const char *filename)
(struct inotify_event *) &buf[event];

if (ev->mask & IN_MODIFY)
- roll_file(filename, &size);
+ roll_file(filename, &size, out);
else {
close(wd);
wd = -1;
@@ -187,33 +187,33 @@ static int follow_by_inotify(FILE *fp, const char *filename)
}
#endif /* HAVE_INOTIFY_INIT */

-static FILE *dump(FILE *fp, const char *filename, int follow)
+static FILE *dump(FILE *in, const char *filename, int follow, FILE *out)
{
struct utmp ut;

if (follow)
- fseek(fp, -10 * sizeof(ut), SEEK_END);
+ fseek(in, -10 * sizeof(ut), SEEK_END);

- while (fread(&ut, sizeof(ut), 1, fp) == 1)
- print_utline(ut);
+ while (fread(&ut, sizeof(ut), 1, in) == 1)
+ print_utline(ut, out);

if (!follow)
- return fp;
+ return in;

#ifdef HAVE_INOTIFY_INIT
- if (follow_by_inotify(fp, filename) == 0)
+ if (follow_by_inotify(in, filename, out) == 0)
return NULL; /* file already closed */
else
#endif
/* fallback for systems without inotify or with non-free
* inotify instances */
for (;;) {
- while (fread(&ut, sizeof(ut), 1, fp) == 1)
- print_utline(ut);
+ while (fread(&ut, sizeof(ut), 1, in) == 1)
+ print_utline(ut, out);
sleep(1);
}

- return fp;
+ return in;
}

@@ -245,7 +245,7 @@ static int gettok(char *line, char *dest, int size, int eatspace)
return eaten + 1;
}

-static void undump(FILE *fp)
+static void undump(FILE *in, FILE *out)
{
struct utmp ut;
char s_addr[16], s_time[29], *linestart, *line;
@@ -255,7 +255,7 @@ static void undump(FILE *fp)
s_addr[15] = 0;
s_time[28] = 0;

- while (fgets(linestart, 1023, fp)) {
+ while (fgets(linestart, 1023, in)) {
line = linestart;
memset(&ut, '\0', sizeof(ut));
sscanf(line, "[%hd] [%d] [%4c] ", &ut.ut_type, &ut.ut_pid, ut.ut_id);
@@ -270,7 +270,7 @@ static void undump(FILE *fp)
ut.ut_addr = inet_addr(s_addr);
ut.ut_time = strtotime(s_time);

- ignore_result( fwrite(&ut, sizeof(ut), 1, stdout) );
+ ignore_result( fwrite(&ut, sizeof(ut), 1, out) );

++count;
}
@@ -286,8 +286,9 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
_(" %s [options] [filename]\n"), program_invocation_short_name);

fputs(USAGE_OPTIONS, out);
- fputs(_(" -f, --follow output appended data as the file grows\n"
- " -r, --reverse write back dumped data into utmp file\n"), out);
+ fputs(_(" -f, --follow output appended data as the file grows\n"), out);
+ fputs(_(" -r, --reverse write back dumped data into utmp file\n"), out);
+ fputs(_(" -o, --output <file> write to file instead of standard output\n"), out);
fputs(USAGE_HELP, out);
fputs(USAGE_VERSION, out);

@@ -298,13 +299,14 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
int main(int argc, char **argv)
{
int c;
- FILE *fp = NULL;
+ FILE *in = NULL, *out = NULL;
int reverse = 0, follow = 0;
const char *filename = NULL;

static const struct option longopts[] = {
{ "follow", 0, 0, 'f' },
{ "reverse", 0, 0, 'r' },
+ { "output", required_argument, 0, 'o' },
{ "help", 0, 0, 'h' },
{ "version", 0, 0, 'V' },
{ NULL, 0, 0, 0 }
@@ -315,7 +317,7 @@ int main(int argc, char **argv)
textdomain(PACKAGE);
atexit(close_stdout);

- while ((c = getopt_long(argc, argv, "frhV", longopts, NULL)) != -1) {
+ while ((c = getopt_long(argc, argv, "fro:hV", longopts, NULL)) != -1) {
switch (c) {
case 'r':
reverse = 1;
@@ -325,6 +327,13 @@ int main(int argc, char **argv)
follow = 1;
break;

+ case 'o':
+ out = fopen(optarg, "w");
+ if (!out)
+ err(EXIT_FAILURE, _("cannot open %s"),
+ optarg);
+ break;
+
case 'h':
usage(stdout);
break;
@@ -336,28 +345,35 @@ int main(int argc, char **argv)
}
}

+ if (!out)
+ out = stdout;
+
if (optind < argc) {
filename = argv[optind];
- fp = fopen(filename, "r");
- if (!fp)
+ in = fopen(filename, "r");
+ if (!in)
err(EXIT_FAILURE, _("cannot open %s"), filename);
} else {
if (follow)
errx(EXIT_FAILURE, _("following standard input is unsupported"));
filename = "/dev/stdin";
- fp = stdin;
+ in = stdin;
}

if (reverse) {
fprintf(stderr, _("Utmp undump of %s\n"), filename);
- undump(fp);
+ undump(in, out);
} else {
fprintf(stderr, _("Utmp dump of %s\n"), filename);
- fp = dump(fp, filename, follow);
+ in = dump(in, filename, follow, out);
}

- if (fp && fp != stdin)
- fclose(fp);
+ if (out != stdout)
+ if (close_stream(out))
+ err(EXIT_FAILURE, _("write failed"));
+
+ if (in && in != stdin)
+ fclose(in);

return EXIT_SUCCESS;
}
--
1.8.2.1