commit c21af69f29ca5a55385a926fdac4a8e6c8fb6d37 Author: Andrea Shepard <andrea@persephoneslair.org> Date: Wed Jun 20 14:43:50 2012 -0700 Refactor unsigned int hex formatting out of format_helper_exit_status() in util.c --- src/common/util.c | 154 +++++++++++++++++++++++++++++++++-------------------- src/common/util.h | 2 + 2 files changed, 99 insertions(+), 57 deletions(-) diff --git a/src/common/util.c b/src/common/util.c index 63a8aff..79e7a70 100644 --- a/src/common/util.c +++ b/src/common/util.c @@ -3191,6 +3191,61 @@ tor_join_win_cmdline(const char *argv[]) return joined_argv; } +/** + * Helper function to output hex numbers, called by + * format_helper_exit_status(). This writes the hexadecimal digits of x into + * buf, up to max_len digits, and returns the actual number of digits written. + * If there is insufficient space, it will write nothing and return 0. + * + * This accepts an unsigned int because format_helper_exit_status() needs to + * call it with a signed int and an unsigned char, and since the C standard + * does not guarantee that an int is wider than a char (an int must be at + * least 16 bits but it is permitted for a char to be that wide as well), we + * can't assume a signed int is sufficient to accomodate an unsigned char. + * Thus, format_helper_exit_status() will still need to emit any require '-' + * on its own. + */ + +int +format_hex_number_for_helper_exit_status(unsigned int x, char *buf, + int max_len) +{ + int len; + unsigned int tmp; + char *cur; + + /* Sanity check */ + if (!buf || max_len <= 0) + return 0; + + /* How many chars do we need for x? */ + if (x > 0) { + len = 0; + tmp = x; + while (tmp > 0) { + tmp >>= 4; + ++len; + } + } + else len = 1; + + /* Bail if we would go past the end of the buffer */ + if (len > max_len) + return 0; + + /* Point to last one */ + cur = buf + len - 1; + + /* Convert x to hex */ + do { + *cur-- = "0123456789ABCDEF"[x & 0xf]; + x >>= 4; + } while (x != 0 && cur >= buf); + + /* Return len */ + return len; +} + /** 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. @@ -3208,9 +3263,9 @@ void format_helper_exit_status(unsigned char child_state, int saved_errno, char *hex_errno) { - unsigned int unsigned_errno, len, tmp_uint; - char *cur, *tmp; - unsigned char tmp_uchar; + unsigned int unsigned_errno; + int written, left; + char *cur; size_t i; /* Fill hex_errno with spaces, and a trailing newline (memset may @@ -3226,87 +3281,72 @@ format_helper_exit_status(unsigned char child_state, int saved_errno, unsigned_errno = (unsigned int) saved_errno; } - /* How many chars do we need for child_state ? */ - if ( child_state > 0 ) { - len = 0; - tmp_uchar = child_state; - while (tmp_uchar > 0) { - tmp_uchar >>= 4; - ++len; - } - } - else len = 1; + /* + * Count how many chars of space we have left, and keep a pointer into the + * current point in the buffer. + */ + left = HEX_ERRNO_SIZE; + cur = hex_errno; - /* Bail if we would go past the end (on this or the '/') */ - if ( len + 2 > HEX_ERRNO_SIZE) + /* Emit child_state */ + written = format_hex_number_for_helper_exit_status(child_state, + cur, left); + if (written <= 0) goto err; - /* Point to last one */ - cur = hex_errno + len - 1; - - /* Convert child_state to hex */ - do { - *cur-- = "0123456789ABCDEF"[child_state & 0xf]; - child_state >>= 4; - } while (child_state != 0 && cur >= hex_errno); - - /* Check for overflow on first iteration of the loop */ - if (cur + 1 < hex_errno) + /* Adjust left and cur */ + left -= written; + cur += written; + if (left <= 0) goto err; /* Now the '/' */ - hex_errno[len] = '/'; - - /* Save a pointer to the start of second number */ - tmp = hex_errno + len; + *cur = '/'; - /* How many chars do we need for unsigned_errno? */ - if ( unsigned_errno > 0 ) { - len = 0; - tmp_uint = unsigned_errno; - while (tmp_uint > 0) { - tmp_uint >>= 4; - ++len; - } - } - else len = 1; + /* Adjust left and cur */ + ++cur; + --left; + if (left <= 0) + goto err; /* Need minus? */ if (saved_errno < 0) { - if ( tmp + 1 - hex_errno > (ptrdiff_t)(HEX_ERRNO_SIZE) ) + *cur = '-'; + ++cur; + --left; + if (left <= 0) goto err; - - *(++tmp) = '-'; } - /* Last check for space */ - if ( tmp + len + 2 - hex_errno > (ptrdiff_t)(HEX_ERRNO_SIZE) ) + /* Emit unsigned_errno */ + written = format_hex_number_for_helper_exit_status(unsigned_errno, + cur, left); + + if (written <= 0) goto err; - /* Point to last one */ - cur = tmp + len; + /* Adjust left and cur */ + left -= written; + cur += written; - /* Convert unsigned_errno to hex */ - do { - *cur-- = "0123456789ABCDEF"[unsigned_errno & 0xf]; - unsigned_errno >>= 4; - } while (unsigned_errno != 0 && cur >= tmp); + /* Check that we have enough space left for a newline */ + if (left <= 0) + goto err; /* Emit the newline and NUL */ - cur = tmp + len; - *(++cur) = '\n'; - *(++cur) = '\0'; + *cur++ = '\n'; + *cur++ = '\0'; goto done; -err: + err: /* * In error exit, just write a '\0' in the first char so whatever called * this at least won't fall off the end. */ *hex_errno = '\0'; -done: + done: return; } diff --git a/src/common/util.h b/src/common/util.h index a2b196c..6b7c6fb 100644 --- a/src/common/util.h +++ b/src/common/util.h @@ -471,6 +471,8 @@ void tor_process_handle_destroy(process_handle_t *process_handle, #ifdef UTIL_PRIVATE /* Prototypes for private functions only used by util.c (and unit tests) */ +int format_hex_number_for_helper_exit_status(unsigned int x, char *buf, + int max_len); void format_helper_exit_status(unsigned char child_state, int saved_errno, char *hex_errno);