parse_seccomp_policy: Allow to read from stdin
When the filename is "-", parse_seccomp_policy will read the policy from
stdin instead of a file.
Bug: None
Test: echo 'read: 1' | ./parse_seccomp_policy --dump - | \
./libseccomp/tools/scmp_bpf_disasm
Change-Id: I150d5536e2672a843661be3605e652d250eede7a
diff --git a/parse_seccomp_policy.cc b/parse_seccomp_policy.cc
index 18cff96..c563a4a 100644
--- a/parse_seccomp_policy.cc
+++ b/parse_seccomp_policy.cc
@@ -5,6 +5,7 @@
#include <getopt.h>
#include <stdio.h>
+#include <string.h>
#include <string>
@@ -29,7 +30,10 @@
void Usage(const char* progn, int status) {
// clang-format off
fprintf(status ? stderr : stdout,
- "Usage: %s [--dump[=<output.bpf>]] <policy file>\n"
+ "Usage: %s [--dump[=<output.bpf>]] [<policy file>]\n"
+ "\n"
+ "With no <policy file>, or when <policy file> is -, reads from standard input.\n"
+ "\n"
" --dump[=<output>]: Dump the BPF program into stdout (or <output>,\n"
" -d[<output>]: if provided). Useful if you want to inspect it\n"
" with libseccomp's scmp_bpf_disasm.\n",
@@ -66,12 +70,11 @@
}
}
- // There should be at least one additional unparsed argument: the
+ FILE* f = stdin;
+ // If there is at least one additional unparsed argument, treat it as the
// policy script.
- if (argc == optind)
- Usage(argv[0], 1);
-
- FILE* f = fopen(argv[optind], "re");
+ if (argc > optind && strcmp(argv[optind], "-") != 0)
+ f = fopen(argv[optind], "re");
if (!f)
pdie("fopen(%s) failed", argv[1]);
