From Graeme Hewson:

	Allow "-" as the output file name in Wiretap, referring to the
	standard error.

	Optimize the capture loop.

Fix some of the error-message printing code in Ethereal and Tethereal.

Have Wiretap check whether it can seek on a file descriptor, and pass
the results of that test to the file-type-specific "open for output"
routine.  Have the "open for output" routines for files where we need to
seek when writing the file return an error if seeks don't work.

svn path=/trunk/; revision=5884

1 files changed, 45 insertions, 21 deletions

diff --git a/wiretap/file.c b/wiretap/file.c
index 036b9057dc..3253ecb974 100644
--- a/wiretap/file.c
+++ b/wiretap/file.c
@@ -1,6 +1,6 @@
 /* file.c
  *
- * $Id: file.c,v 1.93 2002/06/27 22:46:47 guy Exp $
+ * $Id: file.c,v 1.94 2002/07/16 07:15:08 guy Exp $
  *
  * Wiretap Library
  * Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
@@ -308,7 +308,7 @@ static const struct file_type_info {
 	const char *name;
 	const char *short_name;
 	int	(*can_write_encap)(int);
-	int	(*dump_open)(wtap_dumper *, int *);
+	int	(*dump_open)(wtap_dumper *, gboolean, int *);
 } dump_open_table[WTAP_NUM_FILE_TYPES] = {
 	/* WTAP_FILE_UNKNOWN */
 	{ NULL, NULL,
@@ -513,20 +513,26 @@ wtap_dumper* wtap_dump_open(const char *filename, int filetype, int encap,
 	if (wdh == NULL)
 		return NULL;	/* couldn't allocate it */
 
-	/* In case "fopen()" fails but doesn't set "errno", set "errno"
-	   to a generic "the open failed" error. */
-	errno = WTAP_ERR_CANT_OPEN;
-	fh = fopen(filename, "wb");
-	if (fh == NULL) {
-		*err = errno;
-		return NULL;	/* can't create file */
+	/* Empty filename means stdout */
+	if (*filename == '\0')
+		wdh->fh = stdout;
+	else {
+		/* In case "fopen()" fails but doesn't set "errno", set "errno"
+		   to a generic "the open failed" error. */
+		errno = WTAP_ERR_CANT_OPEN;
+		fh = fopen(filename, "wb");
+		if (fh == NULL) {
+			*err = errno;
+			return NULL;	/* can't create file */
+		}
+		wdh->fh = fh;
 	}
-	wdh->fh = fh;
 
 	if (!wtap_dump_open_finish(wdh, filetype, err)) {
 		/* Get rid of the file we created; we couldn't finish
 		   opening it. */
-		unlink(filename);
+		if (wdh->fh != stdout)
+			unlink(filename);
 		return NULL;
 	}
 	return wdh;
@@ -604,12 +610,27 @@ static wtap_dumper* wtap_dump_alloc_wdh(int filetype, int encap, int snaplen,
 
 static gboolean wtap_dump_open_finish(wtap_dumper *wdh, int filetype, int *err)
 {
+	int fd;
+	gboolean cant_seek;
+
+	/* Can we do a seek on the file descriptor?
+	   If not, note that fact. */
+	fd = fileno(wdh->fh);
+	if (lseek(fd, 1, SEEK_CUR) == -1)
+	  cant_seek = TRUE;
+	else {
+	  /* Undo the seek. */
+	  lseek(fd, 0, SEEK_SET);
+	  cant_seek = FALSE;
+	}
+
 	/* Now try to open the file for writing. */
-	if (!(*dump_open_table[filetype].dump_open)(wdh, err)) {
+	if (!(*dump_open_table[filetype].dump_open)(wdh, cant_seek, err)) {
 		/* The attempt failed.  Close the stream for the file.
 		   NOTE: this means the FD handed to "wtap_dump_fdopen()"
 		   will be closed if the open fails. */
-		fclose(wdh->fh);
+		if (wdh->fh != stdout)
+			fclose(wdh->fh);
 
 		/* Now free up the dumper handle. */
 		g_free(wdh);
@@ -640,15 +661,18 @@ gboolean wtap_dump_close(wtap_dumper *wdh, int *err)
 			ret = FALSE;
 	}
 	errno = WTAP_ERR_CANT_CLOSE;
-	if (fclose(wdh->fh) == EOF) {
-		if (ret) {
-			/* The per-format close function succeeded,
-			   but the fclose didn't.  Save the reason
-			   why, if our caller asked for it. */
-			if (err != NULL)
-				*err = errno;
+	/* Don't close stdout */
+	if (wdh->fh != stdout) {
+		if (fclose(wdh->fh) == EOF) {
+			if (ret) {
+				/* The per-format close function succeeded,
+				   but the fclose didn't.  Save the reason
+				   why, if our caller asked for it. */
+				if (err != NULL)
+					*err = errno;
+			}
+			ret = FALSE;
 		}
-		ret = FALSE;
 	}
 	if (wdh->dump.opaque != NULL)
 		g_free(wdh->dump.opaque);