dynstr.c: Fix memory leak if realloc(3) fails
According to C99 §7.20.3.4: If memory for the new object cannot be allocated, the old object is not deallocated and its value is unchanged. Therefore, a temporary pointer must be used to ensure the original object can still be deallocated should realloc(3) return a null pointer.
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32
dynstr.c
32
dynstr.c
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@ -40,13 +40,13 @@ enum dynstr_err dynstr_vappend(struct dynstr *const d, const char *const format,
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{
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const size_t src_len = vsnprintf(NULL, 0, format, ap);
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const size_t new_len = d->len + src_len + 1;
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char *const s = realloc(d->str, new_len * sizeof *d->str);
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d->str = realloc(d->str, new_len * sizeof *d->str);
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if (d->str)
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if (s)
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{
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vsprintf(d->str + d->len, format, apc);
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vsprintf(s + d->len, format, apc);
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d->len += src_len;
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d->str = s;
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}
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else
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{
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@ -79,25 +79,26 @@ enum dynstr_err dynstr_vprepend(struct dynstr *const d, const char *const format
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{
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const size_t src_len = vsnprintf(NULL, 0, format, ap);
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const size_t new_len = d->len + src_len + 1;
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char *const s = realloc(d->str, new_len * sizeof *d->str);
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d->str = realloc(d->str, new_len * sizeof *d->str);
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if (d->str && d->len)
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if (s && d->len)
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{
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/* Keep byte that will be removed by later call to vsprintf. */
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const char c = *d->str;
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const char c = *s;
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for (size_t i = new_len - 1, j = d->len; j <= d->len; i--, j--)
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{
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d->str[i] = d->str[j];
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s[i] = s[j];
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}
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vsprintf(d->str, format, apc);
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d->str[src_len] = c;
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vsprintf(s, format, apc);
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s[src_len] = c;
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d->str = s;
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}
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else if (!d->len)
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{
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vsprintf(d->str + d->len, format, apc);
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vsprintf(s + d->len, format, apc);
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d->str = s;
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}
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else
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{
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@ -128,12 +129,13 @@ enum dynstr_err dynstr_dup(struct dynstr *const dst, const struct dynstr *const
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if (src->len && src->str)
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{
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const size_t sz = (src->len + 1) * sizeof *dst->str;
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dst->str = realloc(dst->str, sz);
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char *const s = realloc(dst->str, sz);
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if (dst->str)
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if (s)
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{
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memcpy(dst->str, src->str, sz);
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memcpy(s, src->str, sz);
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dst->len = src->len;
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dst->str = s;
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}
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else
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{
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