From: Eugene Syromyatnikov <evgsyr@gmail.com>
Date: Wed, 30 Nov 2016 20:43:51 +0000 (+0300)
Subject: Print syscall names only for defined syscalls
X-Git-Tag: v4.15~42
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9936b91d9f77f799d1c9858743de7841bfb31ba4;p=strace

Print syscall names only for defined syscalls

The string literal "__NR_syscall_4294967295" is semantically incorrect
as there is no such constant defined.

* syscall.c (syscall_name): Return NULL if there is no syscall
corresponding to the given number.
* defs.h (syscall_name): Document this behaviour.
* printsiginfo.c (print_si_info): Print syscall name with "__NR_" prefix
only if there is a syscall corresponding to si_syscall number; print
a plain syscall number otherwise.
* tests/ptrace.c (main): Update expected output.
---

diff --git a/defs.h b/defs.h
index 3a0c0636..1e95a65b 100644
--- a/defs.h
+++ b/defs.h
@@ -457,6 +457,13 @@ extern void call_summary(FILE *);
 extern void clear_regs(void);
 extern void get_regs(pid_t pid);
 extern int get_scno(struct tcb *tcp);
+/**
+ * Convert syscall number to syscall name.
+ *
+ * @param scno Syscall number.
+ * @return     String literal corresponding to the syscall number in case latter
+ *             is valid; NULL otherwise.
+ */
 extern const char *syscall_name(long scno);
 extern const char *err_name(unsigned long err);
 
diff --git a/printsiginfo.c b/printsiginfo.c
index 1f4a8258..e92738ed 100644
--- a/printsiginfo.c
+++ b/printsiginfo.c
@@ -189,13 +189,21 @@ print_si_info(const siginfo_t *sip)
 			}
 			break;
 #ifdef HAVE_SIGINFO_T_SI_SYSCALL
-		case SIGSYS:
+		case SIGSYS: {
+			const char *scname =
+				syscall_name((unsigned) sip->si_syscall);
+
 			tprints(", si_call_addr=");
 			printaddr((unsigned long) sip->si_call_addr);
-			tprintf(", si_syscall=__NR_%s, si_arch=",
-				syscall_name((unsigned) sip->si_syscall));
+			tprints(", si_syscall=");
+			if (scname)
+				tprintf("__NR_%s", scname);
+			else
+				tprintf("%u", (unsigned) sip->si_syscall);
+			tprints(", si_arch=");
 			printxval(audit_arch, sip->si_arch, "AUDIT_ARCH_???");
 			break;
+		}
 #endif
 		default:
 			if (sip->si_pid || sip->si_uid)
diff --git a/syscall.c b/syscall.c
index 0488234e..36f32799 100644
--- a/syscall.c
+++ b/syscall.c
@@ -990,14 +990,7 @@ shuffle_scno(unsigned long scno)
 const char *
 syscall_name(long scno)
 {
-	static char buf[sizeof("syscall_%lu") + sizeof(long)*3];
-
-	if (SCNO_IS_VALID(scno))
-		return sysent[scno].sys_name;
-	else {
-		sprintf(buf, "syscall_%lu", scno);
-		return buf;
-	}
+	return SCNO_IS_VALID(scno) ? sysent[scno].sys_name: NULL;
 }
 
 const char *
diff --git a/tests/ptrace.c b/tests/ptrace.c
index 1dcfec3b..c046fa48 100644
--- a/tests/ptrace.c
+++ b/tests/ptrace.c
@@ -345,7 +345,7 @@ main(void)
 	do_ptrace(PTRACE_SETSIGINFO, pid, bad_request, (unsigned long) sip);
 	printf("ptrace(PTRACE_SETSIGINFO, %u, %#lx, {si_signo=SIGSYS"
 	       ", si_code=SYS_SECCOMP, si_errno=ENOENT, si_call_addr=%p"
-	       ", si_syscall=__NR_syscall_%u, si_arch=AUDIT_ARCH_X86_64})"
+	       ", si_syscall=%u, si_arch=AUDIT_ARCH_X86_64})"
 	       " = %s\n",
 	       (unsigned) pid, bad_request, sip->si_call_addr, sip->si_syscall,
 	       errstr);