virSkipSpacesBackwards: Turn @endp into const

The aim of virSkipSpacesBackwards() is find the first space
trailing character in given string, For instance, if the input is
"Something whitespacey   ", then the output should be pointing to
the very first space after "y".

Problem here is that the input string is constant, but the
returned pointer is non-constant. This is confusing, a caller
shouldn't be able to modify the string, since the input was a
constant string.

Therefore, make the function return a const pointer too.

Under the hood the function used virTrimSpaces() which under some
circumstances could modify the input string. A trick was used to
hide this fact away, but to be double sure rewrite the function's
body.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Tested-by: Jaroslav Suchanek <jsuchane@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

diff --git a/src/util/virstring.c b/src/util/virstring.c
index 7249ab4e7c5f09dd4ad537ab956cddf12d53e1a6..e001d76bf181617458b8c2a1b3c4cb3021c84ec1 100644 (file)
--- a/src/util/virstring.c
+++ b/src/util/virstring.c
@@ -484,17 +484,23 @@ virTrimSpaces(char *str, char **endp)
  * but spaces.
  */
 void
-virSkipSpacesBackwards(const char *str, char **endp)
+virSkipSpacesBackwards(const char *str,
+                       const char **endp)
 {
-    /* Casting away const is safe, since virTrimSpaces does not
-     * modify string with this particular usage.  */
-    char *s = (char*) str;
+    const char *end;
 
     if (!*endp)
-        *endp = s + strlen(s);
-    virTrimSpaces(s, endp);
-    if (s == *endp)
+        end = str + strlen(str);
+    else
+        end = *endp;
+
+    while (end > str && g_ascii_isspace(end[-1]))
+        end--;
+
+    if (str == end)
         *endp = NULL;
+    else
+        *endp = end;
 }
 
 /**

diff --git a/src/util/virstring.h b/src/util/virstring.h
index 3d880faf0cc94f7bb6e0aa01e56a3e79c7c0a545..8c2208ece807f2b8ecc2d63bea9ee757158b5462 100644 (file)
--- a/src/util/virstring.h
+++ b/src/util/virstring.h
@@ -75,7 +75,7 @@ void virSkipSpaces(const char **str) ATTRIBUTE_NONNULL(1);
 void virSkipSpacesAndBackslash(const char **str) ATTRIBUTE_NONNULL(1);
 void virSkipToDigit(const char **str) ATTRIBUTE_NONNULL(1);
 void virTrimSpaces(char *str, char **endp) ATTRIBUTE_NONNULL(1);
-void virSkipSpacesBackwards(const char *str, char **endp)
+void virSkipSpacesBackwards(const char *str, const char **endp)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
 bool virStringIsEmpty(const char *str);

diff --git a/src/util/virsysinfo.c b/src/util/virsysinfo.c
index 0f12a8964f08f8ee75e25cad332b0499c20c6cfb..c017ad34b7cc53bf4730f73d553e251ea8e8c414 100644 (file)
--- a/src/util/virsysinfo.c
+++ b/src/util/virsysinfo.c
@@ -625,7 +625,7 @@ virSysinfoParseBIOS(const char *base, virSysinfoBIOSDef **bios)
 {
     int ret = -1;
     const char *cur;
-    char *eol = NULL;
+    const char *eol = NULL;
     virSysinfoBIOSDef *def;
 
     if ((cur = strstr(base, "BIOS Information")) == NULL)
@@ -679,7 +679,7 @@ virSysinfoParseX86System(const char *base, virSysinfoSystemDef **sysdef)
 {
     int ret = -1;
     const char *cur;
-    char *eol = NULL;
+    const char *eol = NULL;
     virSysinfoSystemDef *def;
 
     if ((cur = strstr(base, "System Information")) == NULL)
@@ -755,7 +755,7 @@ virSysinfoParseX86BaseBoard(const char *base,
                             size_t *nbaseBoard)
 {
     const char *cur;
-    char *eol = NULL;
+    const char *eol = NULL;
     virSysinfoBaseBoardDef *boards = NULL;
     size_t nboards = 0;
 
@@ -832,7 +832,7 @@ virSysinfoParseX86Chassis(const char *base,
 {
     int ret = -1;
     const char *cur;
-    char *eol = NULL;
+    const char *eol = NULL;
     virSysinfoChassisDef *def;
 
     if ((cur = strstr(base, "Chassis Information")) == NULL)
@@ -942,7 +942,7 @@ virSysinfoParseOEMStrings(const char *base,
     while ((cur = strstr(cur, "String "))) {
         char *collon = NULL;
         unsigned int idx = 0;
-        char *eol;
+        const char *eol;
 
         cur += 7;
 
@@ -1005,7 +1005,7 @@ static void
 virSysinfoParseX86Processor(const char *base, virSysinfoDef *ret)
 {
     const char *cur, *tmp_base;
-    char *eol;
+    const char *eol;
     virSysinfoProcessorDef *processor;
 
     while ((tmp_base = strstr(base, "Processor Information")) != NULL) {
@@ -1103,7 +1103,7 @@ static void
 virSysinfoParseX86Memory(const char *base, virSysinfoDef *ret)
 {
     const char *cur, *tmp_base;
-    char *eol;
+    const char *eol;
     virSysinfoMemoryDef *memory;
 
     while ((tmp_base = strstr(base, "Memory Device")) != NULL) {

diff --git a/tests/virstringtest.c b/tests/virstringtest.c
index a9c8e621ceb0980ecde176566ecca628c5fed2f2..0792155cc312098894f75da5193ee6931ac5f037 100644 (file)
--- a/tests/virstringtest.c
+++ b/tests/virstringtest.c
@@ -118,7 +118,7 @@ static int
 testSkipSpacesBackwards(const void *opaque G_GNUC_UNUSED)
 {
     const char *str = TEST_STR TEST_SPACES;
-    char *eol = NULL;
+    const char *eol = NULL;
 
     virSkipSpacesBackwards(str, &eol);