Introduce str_strip_prefix_len function and STR_STRIP_PREFIX macro

Address proliferation of string prefix check implementations.

* defs.h (str_strip_prefix_len): New inline function.
(STR_STRIP_PREFIX): New macro.
* qualify.c (strip_prefix): Remove.
(parse_inject_token): Use STR_STRIP_PREFIX instead of strip_prefix.
(qualify): Use str_strip_prefix_len.
* socketutils.c (netlink_parse_response): Likewise.
* util.c (printfd): Likewise.

diff --git a/defs.h b/defs.h
index f731fa8cca4239746c4b96c4377e5e8de4281e34..3c8c5a763868a91da3f4661fc2e011c38822b26c 100644 (file)
--- a/defs.h
+++ b/defs.h
@@ -511,6 +511,20 @@ string_to_uint_upto(const char *const str, unsigned int max_val)
 }
 extern int next_set_bit(const void *bit_array, unsigned cur_bit, unsigned size_bits);
 
+/*
+ * Returns STR if it does not start with PREFIX,
+ * or a pointer to the first char in STR after PREFIX.
+ * The length of PREFIX is specified by PREFIX_LEN.
+ */
+static inline const char *
+str_strip_prefix_len(const char *str, const char *prefix, size_t prefix_len)
+{
+       return strncmp(str, prefix, prefix_len) ? str : str + prefix_len;
+}
+
+#define STR_STRIP_PREFIX(str, prefix)  \
+       str_strip_prefix_len((str), (prefix), sizeof(prefix) - 1)
+
 #define QUOTE_0_TERMINATED                      0x01
 #define QUOTE_OMIT_LEADING_TRAILING_QUOTES      0x02
 #define QUOTE_OMIT_TRAILING_0                   0x08

diff --git a/qualify.c b/qualify.c
index 30888e613998c1d6b8d687db9eefa3681393a04a..de1141d666da61e19f8be787fb9ed1398e2944ea 100644 (file)
--- a/qualify.c
+++ b/qualify.c
@@ -414,18 +414,6 @@ handle_inversion:
        }
 }
 
-/*
- * Returns NULL if STR does not start with PREFIX,
- * or a pointer to the first char in STR after PREFIX.
- */
-static const char *
-strip_prefix(const char *prefix, const char *str)
-{
-       size_t len = strlen(prefix);
-
-       return strncmp(prefix, str, len) ? NULL : str + len;
-}
-
 static int
 find_errno_by_name(const char *name)
 {
@@ -446,7 +434,7 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
        const char *val;
        int intval;
 
-       if ((val = strip_prefix("when=", token))) {
+       if ((val = STR_STRIP_PREFIX(token, "when=")) != token) {
                /*
                 *      == 1+1
                 * F    == F+0
@@ -476,7 +464,7 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
                        /* F == F+0 */
                        fopts->step = 0;
                }
-       } else if ((val = strip_prefix("error=", token))) {
+       } else if ((val = STR_STRIP_PREFIX(token, "error=")) != token) {
                if (fopts->rval != INJECT_OPTS_RVAL_DEFAULT)
                        return false;
                intval = string_to_uint_upto(val, MAX_ERRNO_VALUE);
@@ -485,14 +473,16 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
                if (intval < 1)
                        return false;
                fopts->rval = -intval;
-       } else if (!fault_tokens_only && (val = strip_prefix("retval=", token))) {
+       } else if (!fault_tokens_only
+                  && (val = STR_STRIP_PREFIX(token, "retval=")) != token) {
                if (fopts->rval != INJECT_OPTS_RVAL_DEFAULT)
                        return false;
                intval = string_to_uint(val);
                if (intval < 0)
                        return false;
                fopts->rval = intval;
-       } else if (!fault_tokens_only && (val = strip_prefix("signal=", token))) {
+       } else if (!fault_tokens_only
+                  && (val = STR_STRIP_PREFIX(token, "signal=")) != token) {
                intval = sigstr_to_uint(val);
                if (intval < 1 || intval > NSIG_BYTES * 8)
                        return false;
@@ -677,14 +667,14 @@ qualify(const char *str)
        unsigned int i;
 
        for (i = 0; i < ARRAY_SIZE(qual_options); ++i) {
-               const char *p = qual_options[i].name;
-               unsigned int len = strlen(p);
+               const char *name = qual_options[i].name;
+               const size_t len = strlen(name);
+               const char *val = str_strip_prefix_len(str, name, len);
 
-               if (strncmp(str, p, len) || str[len] != '=')
+               if (val == str || *val != '=')
                        continue;
-
+               str = val + 1;
                opt = &qual_options[i];
-               str += len + 1;
                break;
        }
 

diff --git a/socketutils.c b/socketutils.c
index ef8269ce37e67d53ff1d7a1465c99aca8657956e..534c56eb869cece74128073fe4c61fe5c3abbd40 100644 (file)
--- a/socketutils.c
+++ b/socketutils.c
@@ -381,12 +381,7 @@ netlink_parse_response(const char *proto_name, const void *data,
                                diag_msg->ndiag_protocol);
 
        if (netlink_proto) {
-               static const char netlink_prefix[] = "NETLINK_";
-               const size_t netlink_prefix_len =
-                       sizeof(netlink_prefix) -1;
-               if (strncmp(netlink_proto, netlink_prefix,
-                           netlink_prefix_len) == 0)
-                       netlink_proto += netlink_prefix_len;
+               netlink_proto = STR_STRIP_PREFIX(netlink_proto, "NETLINK_");
                if (asprintf(&details, "%s:[%s:%u]", proto_name,
                             netlink_proto, diag_msg->ndiag_portid) < 0)
                        return -1;

diff --git a/util.c b/util.c
index 9b1c411dcdf4f55beca115b06859adc3a322ac58..50334b4f165d25111e5ee746fc6984344489d4eb 100644 (file)
--- a/util.c
+++ b/util.c
@@ -635,17 +635,15 @@ printfd(struct tcb *tcp, int fd)
 {
        char path[PATH_MAX + 1];
        if (show_fd_path && getfdpath(tcp, fd, path, sizeof(path)) >= 0) {
-               static const char socket_prefix[] = "socket:[";
-               const size_t socket_prefix_len = sizeof(socket_prefix) - 1;
-               const size_t path_len = strlen(path);
+               const char *str;
+               size_t len;
+               unsigned long inode;
 
                tprintf("%d<", fd);
-               if (show_fd_path > 1 &&
-                   strncmp(path, socket_prefix, socket_prefix_len) == 0 &&
-                   path[path_len - 1] == ']') {
-                       unsigned long inode =
-                               strtoul(path + socket_prefix_len, NULL, 10);
-
+               if (show_fd_path > 1
+                   && (str = STR_STRIP_PREFIX(path, "socket:[")) != path
+                   && (len = strlen(str)) && str[len - 1] == ']'
+                   && (inode = strtoul(str, NULL, 10))) {
                        if (!print_sockaddr_by_inode_cached(inode)) {
                                const enum sock_proto proto =
                                        getfdproto(tcp, fd);
@@ -653,7 +651,7 @@ printfd(struct tcb *tcp, int fd)
                                        tprints(path);
                        }
                } else {
-                       print_quoted_string(path, path_len,
+                       print_quoted_string(path, strlen(path),
                                            QUOTE_OMIT_LEADING_TRAILING_QUOTES);
                }
                tprints(">");