Check for IO stream failures in various format's truncate/seek operations

For the formats that support seek and/or truncate operations, many of
the C library calls used to determine or set the current position indicator
in the file stream were not being checked.  In some situations, if an error 
occurred, a negative value would be returned from the library call.  This
could then be interpreted inappropriately as positional data.

This patch checks the return values from these library calls before
using them in subsequent operations.

(issue ASTERISK-19655)
Reported by: Matt Jordan

Review: https://reviewboard.asterisk.org/r/1863/
........

Merged revisions 362151 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 362152 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@362153 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 25 insertions, 4 deletions

diff --git a/formats/format_siren7.c b/formats/format_siren7.c
index 2e5182d3c..955323ed2 100644
--- a/formats/format_siren7.c
+++ b/formats/format_siren7.c
@@ -82,11 +82,20 @@ static int siren7seek(struct ast_filestream *fs, off_t sample_offset, int whence
 
 	sample_offset = SAMPLES_TO_BYTES(sample_offset);
 
-	cur = ftello(fs->f);
+	if ((cur = ftello(fs->f)) < 0) {
+		ast_log(AST_LOG_WARNING, "Unable to determine current position in siren7 filestream %p: %s\n", fs, strerror(errno));
+		return -1;
+	}
 
-	fseeko(fs->f, 0, SEEK_END);
+	if (fseeko(fs->f, 0, SEEK_END) < 0) {
+		ast_log(AST_LOG_WARNING, "Unable to seek to end of siren7 filestream %p: %s\n", fs, strerror(errno));
+		return -1;
+	}
 
-	max = ftello(fs->f);
+	if ((max = ftello(fs->f) < 0)) {
+		ast_log(AST_LOG_WARNING, "Unable to determine max position in siren7 filestream %p: %s\n", fs, strerror(errno));
+		return -1;
+	}
 
 	if (whence == SEEK_SET)
 		offset = sample_offset;
@@ -106,7 +115,19 @@ static int siren7seek(struct ast_filestream *fs, off_t sample_offset, int whence
 
 static int siren7trunc(struct ast_filestream *fs)
 {
-	return ftruncate(fileno(fs->f), ftello(fs->f));
+	int fd;
+	off_t cur;
+
+	if ((fd = fileno(fs->f)) < 0) {
+		ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for siren7 filestream %p: %s\n", fs, strerror(errno));
+		return -1;
+	}
+	if ((cur = ftello(fs->f) < 0)) {
+		ast_log(AST_LOG_WARNING, "Unable to determine current position in siren7 filestream %p: %s\n", fs, strerror(errno));
+		return -1;
+	}
+	/* Truncate file to current length */
+	return ftruncate(fd, cur);
 }
 
 static off_t siren7tell(struct ast_filestream *fs)