Add -a and trivial improvements

Signed-off-by: Mattias Andrée <maandree@kth.se>

6 files changed, 66 insertions, 11 deletions

diff --git a/common.h b/common.h
index 0f478b7..3f899fe 100644
--- a/common.h
+++ b/common.h
@@ -115,10 +115,12 @@ const char *get_errno_name(int err);
 const char *get_signum_name(int sig);
 
 /* memory.c */
+extern size_t abbreviate_memory;
 char *get_string(pid_t pid, unsigned long int addr, size_t *lenp, const char **errorp);
 int get_struct(pid_t pid, unsigned long int addr, void *out, size_t size, const char **errorp);
 char *get_memory(pid_t pid, unsigned long int addr, size_t n, const char **errorp);
 char *escape_memory(const char *str, size_t m);
+char *escape_string(const char *str, size_t m);
 char *get_escaped_string(pid_t pid, unsigned long int addr, size_t *lenp, const char **errorp);
 char *get_escaped_memory(pid_t pid, unsigned long int addr, size_t n, const char **errorp);
 
diff --git a/linux/os.h b/linux/os.h
index 59092e1..05253c2 100644
--- a/linux/os.h
+++ b/linux/os.h
@@ -37,6 +37,10 @@
 # define REGARGS(a, b) a, b
 #endif
 
+#if defined(__arm__) || defined(__thumb__)
+# define USE_PTRACE_SET_SYSCALL
+#endif
+
 
 #ifndef KEY_SPEC_THREAD_KEYRING
 # define KEY_SPEC_THREAD_KEYRING         -1
diff --git a/memory.c b/memory.c
index 6a05ead..eb1ea75 100644
--- a/memory.c
+++ b/memory.c
@@ -2,6 +2,9 @@
 #include "common.h"
 
 
+size_t abbreviate_memory = SIZE_MAX;
+
+
 char *
 get_string(pid_t pid, unsigned long int addr, size_t *lenp, const char **errorp)
 {
@@ -133,8 +136,8 @@ istrigraphfinal(char c)
 }
 
 
-char *
-escape_memory(const char *str, size_t m)
+static char *
+escape(const char *str, size_t m, size_t max)
 {
 	char *ret = NULL;
 	const char *s, *end;
@@ -149,8 +152,10 @@ escape_memory(const char *str, size_t m)
 			eprintf("strdup:");
 		return ret;
 	}
+	if (max > m)
+		max = m;
 	add_char(&ret, &size, &len, '"');
-	for (s = str, end = &str[m]; s != end; s++) {
+	for (s = str, end = &str[max]; s != end; s++) {
 		if (n) {
 			add_char(&ret, &size, &len, *s);
 			n -= 1;
@@ -209,12 +214,31 @@ escape_memory(const char *str, size_t m)
 		need_new_string_hex = 0;
 	}
 	add_char(&ret, &size, &len, '"');
+	if (m > max) {
+		add_char(&ret, &size, &len, '.');
+		add_char(&ret, &size, &len, '.');
+		add_char(&ret, &size, &len, '.');
+	}
 	add_char(&ret, &size, &len, '\0');
 	return ret;
 }
 
 
 char *
+escape_memory(const char *str, size_t m)
+{
+	return escape(str, m, abbreviate_memory);
+}
+
+
+char *
+escape_string(const char *str, size_t m)
+{
+	return escape(str, m, SIZE_MAX);
+}
+
+
+char *
 get_escaped_string(pid_t pid, unsigned long int addr, size_t *lenp, const char **errorp)
 {
 	char *r, *ret;
@@ -223,7 +247,7 @@ get_escaped_string(pid_t pid, unsigned long int addr, size_t *lenp, const char *
 		return NULL;
 	}
 	r = get_string(pid, addr, lenp, errorp);
-	ret = escape_memory(r, *lenp);
+	ret = escape_string(r, *lenp);
 	free(r);
 	return ret;
 }
diff --git a/print.c b/print.c
index c8d51e0..77f8f48 100644
--- a/print.c
+++ b/print.c
@@ -764,9 +764,9 @@ print_sockaddr(struct process *proc, const struct sockaddr *addr, socklen_t len)
 		sun = (const struct sockaddr_un *)addr;
 		slen = (size_t)len - offsetof(struct sockaddr_un, sun_path);
 		if (!slen || !sun->sun_path[0] || !memchr(sun->sun_path, 0, slen))
-			str = escape_memory(sun->sun_path, slen);
+			str = escape_string(sun->sun_path, slen);
 		else
-			str = escape_memory(sun->sun_path, strlen(sun->sun_path));
+			str = escape_string(sun->sun_path, strlen(sun->sun_path));
 		tprintf(proc, "{.sun_family = AF_UNIX, .sun_path = %s}", str);
 		free(str);
 		return;
diff --git a/sctrace.1 b/sctrace.1
index 61ebfd5..3014563 100644
--- a/sctrace.1
+++ b/sctrace.1
@@ -3,6 +3,8 @@
 sctrace - Trace system calls
 .SH SYNOPSIS
 .B sctrace
+.RB [ -a
+.IR byte-count ]
 .RB [ -o
 .IR trace-output-file ]
 .RB [ -ft ]
@@ -48,12 +50,21 @@ argument rather than the
 .I command
 argument.
 .TP
+.BR -a " "\fIbyte-count\fP
+Limit the displayed number of bytes in any region
+of uninterpreted memory (this excludes strings
+and structures but includes file I/O) to
+.I byte-count
+bytes. The string
+.B inf
+is interpreted to remove previously applied limit.
+.TP
 .B -f
 Recursively trace all new children and threads.
 This option implies
 .BR -t .
 .TP
-.BR -o " "\fItrace-output-file\fI
+.BR -o " "\fItrace-output-file\fP
 Write trace outputs to the file specified in the
 .I trace-output-file
 argument.
diff --git a/sctrace.c b/sctrace.c
index 320bc3a..976624d 100644
--- a/sctrace.c
+++ b/sctrace.c
@@ -9,7 +9,8 @@ static unsigned long int trace_options = PTRACE_O_EXITKILL | PTRACE_O_TRACESYSGO
 _Noreturn static void
 usage(void)
 {
-	fprintf(stderr, "usage: %s [-o trace-output-file] [-ft] (command | -0 command argv0) [argument] ...\n", argv0);
+	fprintf(stderr, "usage: %s [-a byte-count] [-o trace-output-file] [-ft]"
+	                " (command | -0 command argv0) [argument] ...\n", argv0);
 	exit(1);
 }
 
@@ -123,7 +124,7 @@ handle_event(struct process *proc, int status)
 			proc->state = trace_event == PTRACE_EVENT_CLONE ? CloneParent : ForkParent;
 			handle_syscall(proc);
 		}
-		tprintf(proc2, "\nTracing new process\n");
+		tprintf(proc2, "\nTracing new process with parent %ju\n", (uintmax_t)proc->pid);
 		proc2->state = trace_event == PTRACE_EVENT_FORK ? ForkChild :
 			trace_event == PTRACE_EVENT_VFORK ? VforkChild : CloneChild;
 		handle_syscall(proc2);
@@ -180,17 +181,29 @@ main(int argc, char **argv)
 	char *outfile = NULL;
 	FILE *outfp = stderr;
 	int status, exit_code = 0, with_argv0 = 0, multiprocess = 0, i;
+	char *arg;
 	struct process *proc, *proc2;
 	struct sigaction sa;
 	sigset_t sm;
 
 	/* TODO add option to trace signals with siginfo (-s) */
-	/* TODO add option to truncate long syscall arguments and outputs (-a)
-	 *      This should be useful if your program does a lot of I/O */
 	ARGBEGIN {
 	case '0':
 		with_argv0 = 1;
 		break;
+	case 'a':
+		arg = EARGF(usage());
+		if (!strcmp(arg, "inf")) {
+			abbreviate_memory = SIZE_MAX;
+			break;
+		}
+		if (!isdigit(arg[0]))
+			usage();
+		errno = 0;
+		abbreviate_memory = (size_t)strtoul(arg, &arg, 10);
+		if ((errno && errno != ERANGE) || *arg)
+			usage();
+		break;
 	case 'o':
 		if (outfile)
 			usage();
@@ -286,6 +299,7 @@ main(int argc, char **argv)
 	if (outfp != stderr)
 		fclose(outfp);
 
+	weprintf("Copying exit from %s\n", multiprocess ? "original tracee" : "tracee");
 	if (WIFSIGNALED(exit_code)) {
 		exit_code = WTERMSIG(exit_code);
 		raise(exit_code);