[tor-commits] [tor/master] Refactor out command line formatting
nickm at torproject.org
nickm at torproject.org
Tue Aug 30 19:58:40 UTC 2011
commit bc97f410802d5b9c66bfba6aebeae1ecd70f8857
Author: Steven Murdoch <Steven.Murdoch at cl.cam.ac.uk>
Date: Mon Aug 29 12:26:55 2011 +0100
Refactor out command line formatting
Now correctly handles whitespace, quotes and backslashes. Passes all unit tests.
---
src/common/util.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++----
src/common/util.h | 1 +
src/test/test_util.c | 49 ++++++++++++++++++++++
3 files changed, 150 insertions(+), 8 deletions(-)
diff --git a/src/common/util.c b/src/common/util.c
index dd2d111..87c6fb5 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -2953,6 +2953,105 @@ load_windows_system_library(const TCHAR *library_name)
}
#endif
+/* Format a single argument for being put on a Windows command line.
+ * Returns a newly allocated string */
+static char *
+format_cmdline_argument(const char *arg)
+{
+ char *formatted_arg;
+ char need_quotes;
+ const char *c;
+ int i;
+ int bs_counter = 0;
+ /* Backslash we can point to when one is inserted into the string */
+ const char backslash = '\\';
+
+ /* Smartlist of *char */
+ smartlist_t *arg_chars;
+ arg_chars = smartlist_create();
+
+ /* Quote string if it contains whitespace or is empty */
+ need_quotes = (strchr(arg, ' ') || strchr(arg, '\t') || '\0' == arg[0]);
+
+ /* Build up smartlist of *chars */
+ for (c=arg; *c != '\0'; c++) {
+ if ('"' == *c) {
+ /* Double up backslashes preceding a quote */
+ for (i=0; i<(bs_counter*2); i++)
+ smartlist_add(arg_chars, (void*)&backslash);
+ bs_counter = 0;
+ /* Escape the quote */
+ smartlist_add(arg_chars, (void*)&backslash);
+ smartlist_add(arg_chars, (void*)c);
+ } else if ('\\' == *c) {
+ /* Count backslashes until we know whether to double up */
+ bs_counter++;
+ } else {
+ /* Don't double up slashes preceding a non-quote */
+ for (i=0; i<bs_counter; i++)
+ smartlist_add(arg_chars, (void*)&backslash);
+ bs_counter = 0;
+ smartlist_add(arg_chars, (void*)c);
+ }
+ }
+ /* Don't double up trailing backslashes */
+ for (i=0; i<bs_counter; i++)
+ smartlist_add(arg_chars, (void*)&backslash);
+
+ /* Allocate space for argument, quotes (if needed), and terminator */
+ formatted_arg = tor_malloc(sizeof(char) *
+ (smartlist_len(arg_chars) + (need_quotes?2:0) + 1));
+
+ /* Add leading quote */
+ i=0;
+ if (need_quotes)
+ formatted_arg[i++] = '"';
+
+ /* Add characters */
+ SMARTLIST_FOREACH(arg_chars, char*, c,
+ {
+ formatted_arg[i++] = *c;
+ });
+
+ /* Add trailing quote */
+ if (need_quotes)
+ formatted_arg[i++] = '"';
+ formatted_arg[i] = '\0';
+
+ smartlist_free(arg_chars);
+ return formatted_arg;
+}
+
+/* Format a command line for use on Windows, which takes the command as a
+ * string rather than string array. Follows the rules from "Parsing C++
+ * Command-Line Arguments" in MSDN. Algorithm based on list2cmdline in the
+ * Python subprocess module. Returns a newly allocated string */
+char *
+tor_join_cmdline(const char *argv[])
+{
+ smartlist_t *argv_list;
+ char *joined_argv;
+ int i;
+
+ /* Format each argument and put the result in a smartlist */
+ argv_list = smartlist_create();
+ for (i=0; argv[i] != NULL; i++) {
+ smartlist_add(argv_list, (void *)format_cmdline_argument(argv[i]));
+ }
+
+ /* Join the arguments with whitespace */
+ joined_argv = smartlist_join_strings(argv_list, " ", 0, NULL);
+
+ /* Free the newly allocated arguments, and the smartlist */
+ SMARTLIST_FOREACH(argv_list, char *, arg,
+ {
+ tor_free(arg);
+ });
+ smartlist_free(argv_list);
+
+ return joined_argv;
+}
+
/** Format <b>child_state</b> and <b>saved_errno</b> as a hex string placed in
* <b>hex_errno</b>. Called between fork and _exit, so must be signal-handler
* safe.
@@ -3068,9 +3167,7 @@ tor_spawn_background(const char *const filename, const char **argv,
BOOL retval = FALSE;
SECURITY_ATTRIBUTES saAttr;
- smartlist_t *argv_list;
char *joined_argv;
- int i;
/* process_handle must not be NULL */
tor_assert(process_handle != NULL);
@@ -3116,12 +3213,7 @@ tor_spawn_background(const char *const filename, const char **argv,
/* Windows expects argv to be a whitespace delimited string, so join argv up
*/
- argv_list = smartlist_create();
- for (i=0; argv[i] != NULL; i++) {
- smartlist_add(argv_list, (void *)argv[i]);
- }
-
- joined_argv = smartlist_join_strings(argv_list, " ", 0, NULL);
+ joined_argv = tor_join_cmdline(argv);
ZeroMemory(&(process_handle->pid), sizeof(PROCESS_INFORMATION));
ZeroMemory(&siStartInfo, sizeof(STARTUPINFO));
diff --git a/src/common/util.h b/src/common/util.h
index d8c7370..9cdd8cb 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -393,6 +393,7 @@ ssize_t tor_read_all_from_process_stdout(const process_handle_t process_handle,
char *buf, size_t count);
ssize_t tor_read_all_from_process_stderr(const process_handle_t process_handle,
char *buf, size_t count);
+char *tor_join_cmdline(const char *argv[]);
void format_helper_exit_status(unsigned char child_state,
int saved_errno, char *hex_errno);
diff --git a/src/test/test_util.c b/src/test/test_util.c
index 4568fde..9df7bc6 100644
--- a/src/test/test_util.c
+++ b/src/test/test_util.c
@@ -1555,6 +1555,54 @@ test_util_spawn_background_partial_read(void *ptr)
}
static void
+test_util_join_cmdline(void *ptr)
+{
+ /* Based on some test cases from "Parsing C++ Command-Line Arguments" in MSDN
+ * but we don't exercise all quoting rules because tor_join_cmdline will try
+ * to only generate simple cases for the child process to parse; i.e. we
+ * never embed quoted strings in arguments. */
+
+ const char *argvs[][4] = {
+ {"a", "bb", "CCC", NULL}, // Normal
+ {NULL, NULL, NULL, NULL}, // Empty argument list
+ {"", NULL, NULL, NULL}, // Empty argument
+ {"\"a", "b\"b", "CCC\"", NULL}, // Quotes
+ {"a\tbc", "dd dd", "E", NULL}, // Whitespace
+ {"a\\\\\\b", "de fg", "H", NULL}, // Backslashes
+ {"a\\\"b", "\\c", "D\\", NULL}, // Backslashes before quote
+ {"a\\\\b c", "d", "E", NULL}, // Backslashes not before quote
+ {} // Terminator
+ };
+
+ const char *cmdlines[] = {
+ "a bb CCC",
+ "",
+ "\"\"",
+ "\\\"a b\\\"b CCC\\\"",
+ "\"a\tbc\" \"dd dd\" E",
+ "a\\\\\\b \"de fg\" H",
+ "a\\\\\\\"b \\c D\\",
+ "\"a\\\\b c\" d E",
+ NULL // Terminator
+ };
+
+ int i;
+ char *joined_argv;
+
+ (void)ptr;
+
+ for (i=0; cmdlines[i]!=NULL; i++) {
+ log_info(LD_GENERAL, "Joining argvs[%d], expecting <%s>", i, cmdlines[i]);
+ joined_argv = tor_join_cmdline(argvs[i]);
+ tt_str_op(joined_argv, ==, cmdlines[i]);
+ tor_free(joined_argv);
+ }
+
+ done:
+ ;
+}
+
+static void
test_util_di_ops(void)
{
#define LT -1
@@ -1642,6 +1690,7 @@ struct testcase_t util_tests[] = {
UTIL_TEST(spawn_background_ok, 0),
UTIL_TEST(spawn_background_fail, 0),
UTIL_TEST(spawn_background_partial_read, 0),
+ UTIL_TEST(join_cmdline, 0),
END_OF_TESTCASES
};
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