syscall logging example - print mode_t

Author: GBuella

examples/syscall_desc.c

@@ -34,6 +34,7 @@
 
 #include <stddef.h>
 #include <syscall.h>
+#include <fcntl.h>
 
 #define SARGS(name, r, ...) \
 	[SYS_##name] = {#name, r, {__VA_ARGS__, }}
@@ -42,7 +43,7 @@
 static const struct syscall_desc table[] = {
 	SARGS(read, rdec, arg_fd, arg_, arg_),
 	SARGS(write, rdec, arg_fd, arg_, arg_),
-	SARGS(open, rdec, arg_cstr, arg_open_flags, arg_),
+	SARGS(open, rdec, arg_cstr, arg_open_flags, arg_mode),
 	SARGS(close, rdec, arg_fd),
 	SARGS(stat, rdec, arg_cstr, arg_),
 	SARGS(fstat, rdec, arg_fd, arg_),
@@ -61,7 +62,7 @@ static const struct syscall_desc table[] = {
 	SARGS(pwrite64, rdec, arg_fd, arg_, arg_, arg_),
 	SARGS(readv, rdec, arg_fd, arg_, arg_),
 	SARGS(writev, rdec, arg_fd, arg_, arg_),
-	SARGS(access, rdec, arg_cstr, arg_),
+	SARGS(access, rdec, arg_cstr, arg_mode),
 	SARGS(pipe, rdec, arg_),
 	SARGS(select, rdec, arg_, arg_, arg_, arg_, arg_),
 	SARGS(sched_yield, rdec, arg_none),
@@ -123,19 +124,19 @@ static const struct syscall_desc table[] = {
 	SARGS(chdir, rdec, arg_cstr),
 	SARGS(fchdir, rdec, arg_fd),
 	SARGS(rename, rdec, arg_cstr, arg_cstr),
-	SARGS(mkdir, rdec, arg_cstr, arg_),
+	SARGS(mkdir, rdec, arg_cstr, arg_mode),
 	SARGS(rmdir, rdec, arg_cstr),
-	SARGS(creat, rdec, arg_cstr, arg_),
+	SARGS(creat, rdec, arg_cstr, arg_mode),
 	SARGS(link, rdec, arg_cstr, arg_cstr),
 	SARGS(unlink, rdec, arg_cstr),
 	SARGS(symlink, rdec, arg_cstr, arg_cstr),
 	SARGS(readlink, rdec, arg_cstr, arg_, arg_),
-	SARGS(chmod, rdec, arg_cstr, arg_),
-	SARGS(fchmod, rdec, arg_fd, arg_),
+	SARGS(chmod, rdec, arg_cstr, arg_mode),
+	SARGS(fchmod, rdec, arg_fd, arg_mode),
 	SARGS(chown, rdec, arg_cstr, arg_, arg_),
 	SARGS(fchown, rdec, arg_fd, arg_, arg_),
 	SARGS(lchown, rdec, arg_cstr, arg_, arg_),
-	SARGS(umask, roct, arg_),
+	SARGS(umask, rmode, arg_mode),
 	SARGS(gettimeofday, rdec, arg_, arg_),
 	SARGS(getrlimit, rdec, arg_, arg_),
 	SARGS(getrusage, rdec, arg_, arg_),
@@ -279,9 +280,9 @@ static const struct syscall_desc table[] = {
 	SARGS(inotify_add_watch, rdec, arg_fd, arg_cstr, arg_),
 	SARGS(inotify_rm_watch, rdec, arg_fd, arg_),
 	SARGS(migrate_pages, rdec, arg_, arg_, arg_, arg_),
-	SARGS(openat, rdec, arg_atfd, arg_cstr, arg_open_flags, arg_),
-	SARGS(mkdirat, rdec, arg_atfd, arg_cstr, arg_),
-	SARGS(mknodat, rdec, arg_atfd, arg_cstr, arg_, arg_),
+	SARGS(openat, rdec, arg_atfd, arg_cstr, arg_open_flags, arg_mode),
+	SARGS(mkdirat, rdec, arg_atfd, arg_cstr, arg_mode),
+	SARGS(mknodat, rdec, arg_atfd, arg_cstr, arg_mode, arg_),
 	SARGS(fchownat, rdec, arg_atfd, arg_cstr, arg_, arg_, arg_),
 	SARGS(futimesat, rdec, arg_atfd, arg_cstr, arg_),
 	SARGS(newfstatat, rdec, arg_atfd, arg_cstr, arg_, arg_),
@@ -290,8 +291,8 @@ static const struct syscall_desc table[] = {
 	SARGS(linkat, rdec, arg_atfd, arg_cstr, arg_atfd, arg_cstr, arg_),
 	SARGS(symlinkat, rdec, arg_atfd, arg_cstr, arg_cstr),
 	SARGS(readlinkat, rdec, arg_atfd, arg_cstr, arg_, arg_),
-	SARGS(fchmodat, rdec, arg_atfd, arg_cstr, arg_),
-	SARGS(faccessat, rdec, arg_atfd, arg_cstr, arg_),
+	SARGS(fchmodat, rdec, arg_atfd, arg_cstr, arg_mode),
+	SARGS(faccessat, rdec, arg_atfd, arg_cstr, arg_mode),
 	SARGS(pselect6, rdec, arg_, arg_, arg_, arg_, arg_, arg_),
 	SARGS(ppoll, rdec, arg_, arg_, arg_, arg_, arg_),
 	SARGS(unshare, rdec, arg_),
@@ -394,14 +395,32 @@ static const struct syscall_desc table[] = {
 
 #undef SARGS
 
+static const struct syscall_desc open_without_mode = {
+	.name = "open",
+	.return_type = rdec,
+	.args = {arg_cstr, arg_open_flags, }
+};
+
+static const struct syscall_desc openat_without_mode = {
+	.name = "openat",
+	.return_type = rdec,
+	.args = {arg_atfd, arg_cstr, arg_open_flags, }
+};
+
 const struct syscall_desc *
-get_syscall_desc(long syscall_number)
+get_syscall_desc(long syscall_number, const long args[6])
 {
 	if (syscall_number < 0)
 		return NULL;
 
 	if ((size_t)syscall_number >= (sizeof(table) / sizeof(table[0])))
 		return NULL;
 
+	if (syscall_number == SYS_open && (args[1] & O_CREAT) == 0)
+		return &open_without_mode;
+
+	if (syscall_number == SYS_openat && (args[2] & O_CREAT) == 0)
+		return &openat_without_mode;
+
 	return table + syscall_number;
 }

examples/syscall_desc.h

@@ -39,14 +39,15 @@ enum arg_type {
 	arg_atfd,
 	arg_cstr,
 	arg_open_flags,
+	arg_mode,
 	arg_ /* no special formatting implemented yet, print as hex number */
 };
 
 enum return_type {
 	rhex,
 	rdec,
 	runsigned,
-	roct
+	rmode
 };
 
 struct syscall_desc {
@@ -55,6 +56,7 @@ struct syscall_desc {
 	enum arg_type args[6];
 };
 
-const struct syscall_desc *get_syscall_desc(long syscall_number);
+const struct syscall_desc *get_syscall_desc(long syscall_number,
+					const long args[static 6]);
 
 #endif

examples/syscall_logger.c

@@ -714,9 +714,13 @@ print_runsigned(char *dst, long n)
 }
 
 static char *
-print_roct(char *dst, long n)
+print_mode_t(char *dst, long n)
 {
 	*dst++ = '0';
+	if (n < 0100)
+		*dst++ = '0';
+	if (n < 0010)
+		*dst++ = '0';
 	return print_number(dst, (unsigned long)n, 8);
 }
 
@@ -762,6 +766,9 @@ print_known_syscall(char *dst, const struct syscall_desc *desc,
 		case arg_open_flags:
 			dst = print_open_flags(dst, args[i]);
 			break;
+		case arg_mode:
+			dst = print_mode_t(dst, result);
+			break;
 		default:
 			dst = print_hex(dst, args[i]);
 			break;
@@ -779,18 +786,20 @@ print_known_syscall(char *dst, const struct syscall_desc *desc,
 	case runsigned:
 		dst = print_runsigned(dst, result);
 		break;
-	case roct:
-		dst = print_roct(dst, result);
+	case rmode:
+		dst = print_mode_t(dst, result);
 		break;
 	}
 
 	return dst;
 }
 
 static ssize_t
-print_syscall(char *dst, long syscall_number, const long args[6], long result)
+print_syscall(char *dst, long syscall_number, long args[6], long result)
 {
-	const struct syscall_desc *desc = get_syscall_desc(syscall_number);
+	const struct syscall_desc *desc =
+		get_syscall_desc(syscall_number, args);
+
 	char *c;
 
 	if (desc != NULL)