utils strbuf: Allow the initial size to be zero.

diff --git a/src/utils/strbuf.c b/src/utils/strbuf.c
index bc24fef5e54c19781c5cd4bef7c3a1036e897945..c8e7e633a27452ade2e8bdb85f078cb542e9e63f 100644 (file)
--- a/src/utils/strbuf.c
+++ b/src/utils/strbuf.c
@@ -48,18 +48,19 @@ struct sdb_strbuf {
  */
 
 static int
-strbuf_resize(sdb_strbuf_t *strbuf)
+strbuf_resize(sdb_strbuf_t *strbuf, size_t new_size)
 {
        char *tmp;
 
-       assert(strbuf->size);
+       if (new_size <= strbuf->size)
+               return 0;
 
-       tmp = realloc(strbuf->string, 2 * strbuf->size);
+       tmp = realloc(strbuf->string, new_size);
        if (! tmp)
                return -1;
 
        strbuf->string = tmp;
-       strbuf->size *= 2;
+       strbuf->size = new_size;
        return 0;
 } /* strbuf_resize */
 
@@ -72,20 +73,21 @@ sdb_strbuf_create(size_t size)
 {
        sdb_strbuf_t *strbuf;
 
-       if (! size)
-               return NULL;
-
        strbuf = calloc(1, sizeof(*strbuf));
        if (! strbuf)
                return NULL;
 
-       strbuf->string = malloc(size);
-       if (! strbuf->string) {
-               free(strbuf);
-               return NULL;
+       strbuf->string = NULL;
+       if (size) {
+               strbuf->string = malloc(size);
+               if (! strbuf->string) {
+                       free(strbuf);
+                       return NULL;
+               }
+
+               strbuf->string[0] = '\0';
        }
 
-       strbuf->string[0] = '\0';
        strbuf->size = size;
        strbuf->pos  = 0;
 
@@ -98,7 +100,8 @@ sdb_strbuf_destroy(sdb_strbuf_t *strbuf)
        if (! strbuf)
                return;
 
-       free(strbuf->string);
+       if (strbuf->string)
+               free(strbuf->string);
        free(strbuf);
 } /* sdb_strbuf_destroy */
 
@@ -111,12 +114,16 @@ sdb_strbuf_vappend(sdb_strbuf_t *strbuf, const char *fmt, va_list ap)
        if ((! strbuf) || (! fmt))
                return -1;
 
-       assert(strbuf->string[strbuf->pos] == '\0');
+       assert((strbuf->size == 0) || (strbuf->string[strbuf->pos] == '\0'));
 
        if (strbuf->pos >= strbuf->size)
-               if (strbuf_resize(strbuf))
+               /* use some arbitrary but somewhat reasonable default */
+               if (strbuf_resize(strbuf, strbuf->size ? 2 * strbuf->size : 64))
                        return -1;
 
+       assert(strbuf->size && strbuf->string);
+       assert(strbuf->pos < strbuf->size);
+
        /* 'ap' is invalid after calling vsnprintf; thus copy before using it */
        va_copy(aq, ap);
        status = vsnprintf(strbuf->string + strbuf->pos,
@@ -128,7 +135,7 @@ sdb_strbuf_vappend(sdb_strbuf_t *strbuf, const char *fmt, va_list ap)
        }
 
        if ((size_t)status >= strbuf->size - strbuf->pos) {
-               strbuf_resize(strbuf);
+               strbuf_resize(strbuf, (size_t)status + 1);
 
                /* reset string and try again */
                strbuf->string[strbuf->pos] = '\0';
@@ -160,8 +167,10 @@ sdb_strbuf_vsprintf(sdb_strbuf_t *strbuf, const char *fmt, va_list ap)
        if (! strbuf)
                return -1;
 
-       strbuf->string[0] = '\0';
-       strbuf->pos = 0;
+       if (strbuf->size) {
+               strbuf->string[0] = '\0';
+               strbuf->pos = 0;
+       }
 
        return sdb_strbuf_vappend(strbuf, fmt, ap);
 } /* sdb_strbuf_vsprintf */
@@ -187,6 +196,9 @@ sdb_strbuf_chomp(sdb_strbuf_t *strbuf)
        if (! strbuf)
                return -1;
 
+       assert(strbuf->size || (strbuf->pos < strbuf->size));
+       assert(strbuf->pos <= strbuf->size);
+
        while ((strbuf->pos > 0)
                        && (strbuf->string[strbuf->pos - 1] == '\n')) {
                --strbuf->pos;
@@ -202,6 +214,8 @@ sdb_strbuf_string(sdb_strbuf_t *strbuf)
 {
        if (! strbuf)
                return NULL;
+       if (! strbuf->size)
+               return "";
        return strbuf->string;
 } /* sdb_strbuf_string */