Check for pcap_dump_ftell() failing.

That way, we don't just keep writing if it fails (which it can when
using Capsicum, for example).

diff --git a/tcpdump.c b/tcpdump.c
index 2276961b4109aedc9c4d450882c888624d10cec6..8e07d8f2e1572dc307aafe86e7c40c200f4d3e99 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -2266,67 +2266,74 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
         * larger than Cflag - the last packet written to the
         * file could put it over Cflag.
         */
-       if (Cflag != 0 && pcap_dump_ftell(dump_info->p) > Cflag) {
+       if (Cflag != 0) {
+               long size = pcap_dump_ftell(dump_info->p);
+
+               if (size == -1)
+                       error("ftell fails on output file");
+               if (size > Cflag) {
 #ifdef HAVE_CAPSICUM
-               FILE *fp;
-               int fd;
+                       FILE *fp;
+                       int fd;
 #endif
 
-               /*
-                * Close the current file and open a new one.
-                */
-               pcap_dump_close(dump_info->p);
+                       /*
+                        * Close the current file and open a new one.
+                        */
+                       pcap_dump_close(dump_info->p);
 
-               /*
-                * Compress the file we just closed, if the user asked for it
-                */
-               if (zflag != NULL)
-                       compress_savefile(dump_info->CurrentFileName);
+                       /*
+                        * Compress the file we just closed, if the user
+                        * asked for it.
+                        */
+                       if (zflag != NULL)
+                               compress_savefile(dump_info->CurrentFileName);
 
-               Cflag_count++;
-               if (Wflag > 0) {
-                       if (Cflag_count >= Wflag)
-                               Cflag_count = 0;
-               }
-               if (dump_info->CurrentFileName != NULL)
-                       free(dump_info->CurrentFileName);
-               dump_info->CurrentFileName = (char *)malloc(PATH_MAX + 1);
-               if (dump_info->CurrentFileName == NULL)
-                       error("dump_packet_and_trunc: malloc");
-               MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, Cflag_count, WflagChars);
+                       Cflag_count++;
+                       if (Wflag > 0) {
+                               if (Cflag_count >= Wflag)
+                                       Cflag_count = 0;
+                       }
+                       if (dump_info->CurrentFileName != NULL)
+                               free(dump_info->CurrentFileName);
+                       dump_info->CurrentFileName = (char *)malloc(PATH_MAX + 1);
+                       if (dump_info->CurrentFileName == NULL)
+                               error("dump_packet_and_trunc: malloc");
+                       MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, Cflag_count, WflagChars);
 #ifdef HAVE_LIBCAP_NG
-               capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
-               capng_apply(CAPNG_SELECT_BOTH);
+                       capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
+                       capng_apply(CAPNG_SELECT_BOTH);
 #endif /* HAVE_LIBCAP_NG */
 #ifdef HAVE_CAPSICUM
-               fd = openat(dump_info->dirfd, dump_info->CurrentFileName,
-                   O_CREAT | O_WRONLY | O_TRUNC, 0644);
-               if (fd < 0) {
-                       error("unable to open file %s",
-                           dump_info->CurrentFileName);
-               }
-               fp = fdopen(fd, "w");
-               if (fp == NULL) {
-                       error("unable to fdopen file %s",
-                           dump_info->CurrentFileName);
-               }
-               dump_info->p = pcap_dump_fopen(dump_info->pd, fp);
+                       fd = openat(dump_info->dirfd, dump_info->CurrentFileName,
+                           O_CREAT | O_WRONLY | O_TRUNC, 0644);
+                       if (fd < 0) {
+                               error("unable to open file %s",
+                                   dump_info->CurrentFileName);
+                       }
+                       fp = fdopen(fd, "w");
+                       if (fp == NULL) {
+                               error("unable to fdopen file %s",
+                                   dump_info->CurrentFileName);
+                       }
+                       dump_info->p = pcap_dump_fopen(dump_info->pd, fp);
 #else  /* !HAVE_CAPSICUM */
-               dump_info->p = pcap_dump_open(dump_info->pd, dump_info->CurrentFileName);
+                       dump_info->p = pcap_dump_open(dump_info->pd, dump_info->CurrentFileName);
 #endif
 #ifdef HAVE_LIBCAP_NG
-               capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
-               capng_apply(CAPNG_SELECT_BOTH);
+                       capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
+                       capng_apply(CAPNG_SELECT_BOTH);
 #endif /* HAVE_LIBCAP_NG */
-               if (dump_info->p == NULL)
-                       error("%s", pcap_geterr(pd));
+                       if (dump_info->p == NULL)
+                               error("%s", pcap_geterr(pd));
 #ifdef HAVE_CAPSICUM
-               cap_rights_init(&rights, CAP_SEEK, CAP_WRITE);
-               if (cap_rights_limit(fileno(pcap_dump_file(dump_info->p)),
-                   &rights) < 0 && errno != ENOSYS) {
-                       error("unable to limit dump descriptor");
-               }
+                       cap_rights_init(&rights, CAP_SEEK, CAP_WRITE);
+                       if (cap_rights_limit(fileno(pcap_dump_file(dump_info->p)),
+                           &rights) < 0 && errno != ENOSYS) {
+                               error("unable to limit dump descriptor");
+                       }
 #endif
+               }
        }
 
        pcap_dump((u_char *)dump_info->p, h, sp);