[PATCH v5] Print absolute paths in printpathn when -yy is used
Zubin Mithra
zubin.mithra at gmail.com
Sat Aug 30 19:56:06 UTC 2014
Hi Dmitry,
> print_tracee_cwd() prints a quoted string, while getfdpath() returns
> a raw string.
>
Thank you for the review! Please find below a diff for renameat+renameat2.
diff --git a/defs.h b/defs.h
index 625cac6..a5fd654 100644
--- a/defs.h
+++ b/defs.h
@@ -562,7 +562,8 @@ extern bool iflag;
extern bool count_wallclock;
extern unsigned int qflag;
extern bool not_failing_only;
-extern unsigned int show_fd_path;
+extern bool show_fd_path;
+extern bool show_abs_path;
extern bool hide_log_until_execve;
/* are we filtering traces based on paths? */
extern const char **paths_selected;
@@ -678,6 +679,7 @@ extern void printstr(struct tcb *, long, long);
extern void printnum(struct tcb *, long, const char *);
extern void printnum_int(struct tcb *, long, const char *);
extern void printpath(struct tcb *, long);
+extern void printpathat(struct tcb *, int, long);
extern void printpathn(struct tcb *, long, int);
#define TIMESPEC_TEXT_BUFSIZE (sizeof(long)*3 * 2 + sizeof("{%u, %u}"))
#define TIMEVAL_TEXT_BUFSIZE TIMESPEC_TEXT_BUFSIZE
diff --git a/file.c b/file.c
index 986f446..37495ba 100644
--- a/file.c
+++ b/file.c
@@ -1771,10 +1771,10 @@ static void
decode_renameat(struct tcb *tcp)
{
print_dirfd(tcp, tcp->u_arg[0]);
- printpath(tcp, tcp->u_arg[1]);
+ printpathat(tcp, tcp->u_arg[0], tcp->u_arg[1]);
tprints(", ");
print_dirfd(tcp, tcp->u_arg[2]);
- printpath(tcp, tcp->u_arg[3]);
+ printpathat(tcp, tcp->u_arg[2], tcp->u_arg[3]);
}
int
diff --git a/strace.1 b/strace.1
index 2a24c38..89d7090 100644
--- a/strace.1
+++ b/strace.1
@@ -321,6 +321,9 @@ Print all strings in hexadecimal string format.
.B \-y
Print paths associated with file descriptor arguments.
.TP
+.B \-A
+Print absolute paths instead of relative paths everywhere.
+.TP
.BI "\-a " column
Align return values in a specific column (default column 40).
.TP
diff --git a/strace.c b/strace.c
index 2bc5c67..8b3adb2 100644
--- a/strace.c
+++ b/strace.c
@@ -129,7 +129,8 @@ static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP;
bool not_failing_only = 0;
/* Show path associated with fd arguments */
-unsigned int show_fd_path = 0;
+bool show_fd_path = 0;
+bool show_abs_path = 0;
static bool detach_on_execve = 0;
/* Are we "strace PROG" and need to skip detach on first execve? */
@@ -203,6 +204,7 @@ usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\
-p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\
or: strace -c[df] [-I n] [-e expr]... [-O overhead] [-S sortby]\n\
-p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\
+-A -- print absolute paths instead of relative paths everywhere\n\
-c -- count time, calls, and errors for each syscall and report summary\n\
-C -- like -c but also print regular output\n\
-w -- summarise syscall latency (default is system time)\n\
@@ -216,6 +218,7 @@ usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\
-v -- verbose mode: print unabbreviated argv, stat, termios, etc. args\n\
-x -- print non-ascii strings in hex, -xx -- print all strings in hex\n\
-y -- print paths associated with file descriptor arguments\n\
+-yy -- print absolute paths instead of relative paths everywhere\n\
-h -- print help message, -V -- print version\n\
-a column -- alignment COLUMN for printing syscall results (default %d)\n\
-b execve -- detach on this syscall\n\
@@ -1676,9 +1679,13 @@ init(int argc, char *argv[])
#ifdef USE_LIBUNWIND
"k"
#endif
+ "A"
"D"
"a:e:o:O:p:s:S:u:E:P:I:")) != EOF) {
switch (c) {
+ case 'A':
+ show_abs_path = 1;
+ break;
case 'b':
if (strcmp(optarg, "execve") != 0)
error_msg_and_die("Syscall '%s' for -b isn't supported",
@@ -1734,7 +1741,7 @@ init(int argc, char *argv[])
xflag++;
break;
case 'y':
- show_fd_path++;
+ show_fd_path = 1;
break;
case 'v':
qualify("abbrev=none");
diff --git a/util.c b/util.c
index c78e962..587bbd4 100644
--- a/util.c
+++ b/util.c
@@ -405,7 +405,8 @@ printfd(struct tcb *tcp, int fd)
{
char path[PATH_MAX + 1];
- if (show_fd_path && getfdpath(tcp, fd, path, sizeof(path)) >= 0)
+ if ((show_fd_path || show_abs_path) &&
+ getfdpath(tcp, fd, path, sizeof(path)) >= 0)
tprintf("%d<%s>", fd, path);
else
tprintf("%d", fd);
@@ -560,11 +561,64 @@ string_quote(const char *instr, char *outstr, long len, int size)
}
/*
- * Print path string specified by address `addr' and length `n'.
- * If path length exceeds `n', append `...' to the output.
+ * Encode a path(either cwd or fd path) in a manner fit for printing
+ * before a relative path.
*/
+static void
+encode_path(char *path, int n)
+{
+ char *outstr;
+
+ path[n++] = '/';
+ path[n++] = '\0';
+
+ /* path has n-1 characters followed by a null */
+ outstr = alloca(4 * n); /* 4*(n-1) + 3 for quotes and NUL */
+ string_quote(path, outstr, -1, n);
+ outstr[strlen(outstr)-1] = '\0'; /* Don't print the closing quotes */
+ tprints(outstr);
+}
+
+/*
+ * Print the current working directory of the tracee process
+ */
+static bool
+print_tracee_cwd(struct tcb *tcp)
+{
+ int link_size = sizeof("/proc//cwd") + sizeof(int) * 3;
+ char linkpath[link_size];
+ char cwd[MAXPATHLEN + 2];
+ ssize_t n;
+
+ snprintf(linkpath, link_size, "/proc/%u/cwd", tcp->pid);
+ n = readlink(linkpath, cwd, MAXPATHLEN);
+
+ if (n > 0) {
+ encode_path(cwd, n);
+ return true;
+ }
+ return false;
+}
+
+/*
+ * Print absolute path string corresponding to an `fd`.
+ */
+static bool
+print_tracee_fdpath(struct tcb *tcp, int fd)
+{
+ char path[PATH_MAX + 1];
+ int n;
+
+ n = getfdpath(tcp, fd, path, sizeof(path));
+ if (n > 0) {
+ encode_path(path, n);
+ return true;
+ }
+ return false;
+}
+
void
-printpathn(struct tcb *tcp, long addr, int n)
+printpath_common(struct tcb *tcp, int fd, long addr, int n)
{
char path[MAXPATHLEN + 1];
int nul_seen;
@@ -584,11 +638,29 @@ printpathn(struct tcb *tcp, long addr, int n)
tprintf("%#lx", addr);
else {
char *outstr;
+ bool prefix_printed = false;
path[n] = '\0';
+
+ /* If the call comes from `printpathn' and -y is used */
+ if (fd == -1 && show_fd_path && *path && *path != '/')
+ prefix_printed = print_tracee_cwd(tcp);
+
+ /* If the call comes from `printpathnat' and -A is used */
+ else if (show_abs_path && *path && *path != '/') {
+ if (fd == AT_FDCWD)
+ prefix_printed = print_tracee_cwd(tcp);
+ else
+ prefix_printed = print_tracee_fdpath(tcp, fd);
+ }
+
n++;
outstr = alloca(4 * n); /* 4*(n-1) + 3 for quotes and NUL */
string_quote(path, outstr, -1, n);
+
+ /* Dont print opening quotes if cwd/decoded dirfd is printed */
+ if (prefix_printed)
+ outstr += 1;
tprints(outstr);
if (!nul_seen)
tprints("...");
@@ -596,6 +668,18 @@ printpathn(struct tcb *tcp, long addr, int n)
}
void
+printpathat(struct tcb *tcp, int fd, long addr)
+{
+ printpath_common(tcp, fd, addr, MAXPATHLEN);
+}
+
+void
+printpathn(struct tcb *tcp, long addr, int n)
+{
+ printpath_common(tcp, -1, addr, n);
+}
+
+void
printpath(struct tcb *tcp, long addr)
{
/* Size must correspond to char path[] size in printpathn */
-- zm
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