coverity: Model GLib string allocation partially

Without a model, Coverity can't know that the result of g_strdup()
needs to be fed to g_free().

One way to get such a model is to scan GLib, build a derived model
file with cov-collect-models, and use that when scanning QEMU.
Unfortunately, the Coverity Scan service we use doesn't support that.

Thus, we're stuck with the other way: write a user model.  Doing that
for all of GLib is hardly practical.  I'm doing it for the "String
Utility Functions" we actually use that return dynamically allocated
strings.

In a local scan, this flags 20 additional RESOURCE_LEAKs.  The ones I
checked look genuine.

It also loses a NULL_RETURNS about ppce500_init() using
qemu_find_file() without error checking.  I don't understand why.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/coverity-model.c

@@ -40,6 +40,8 @@ typedef unsigned long long uint64_t;
 typedef long long int64_t;
 typedef _Bool bool;
 
+typedef struct va_list_str *va_list;
+
 /* exec.c */
 
 typedef struct AddressSpace AddressSpace;
@@ -232,6 +234,93 @@ void *g_try_realloc(void *ptr, size_t size)
     return g_try_realloc_n(ptr, 1, size);
 }
 
+/*
+ * GLib string allocation functions
+ */
+
+char *g_strdup(const char *s)
+{
+    char *dup;
+    size_t i;
+
+    if (!s) {
+        return NULL;
+    }
+
+    __coverity_string_null_sink__(s);
+    __coverity_string_size_sink__(s);
+    dup = __coverity_alloc_nosize__();
+    __coverity_mark_as_afm_allocated__(dup, AFM_free);
+    for (i = 0; (dup[i] = s[i]); i++) ;
+    return dup;
+}
+
+char *g_strndup(const char *s, size_t n)
+{
+    char *dup;
+    size_t i;
+
+    __coverity_negative_sink__(n);
+
+    if (!s) {
+        return NULL;
+    }
+
+    dup = g_malloc(n + 1);
+    for (i = 0; i < n && (dup[i] = s[i]); i++) ;
+    dup[i] = 0;
+    return dup;
+}
+
+char *g_strdup_printf(const char *format, ...)
+{
+    char ch, *s;
+    size_t len;
+
+    __coverity_string_null_sink__(format);
+    __coverity_string_size_sink__(format);
+
+    ch = *format;
+
+    s = __coverity_alloc_nosize__();
+    __coverity_writeall__(s);
+    __coverity_mark_as_afm_allocated__(s, AFM_free);
+    return s;
+}
+
+char *g_strdup_vprintf(const char *format, va_list ap)
+{
+    char ch, *s;
+    size_t len;
+
+    __coverity_string_null_sink__(format);
+    __coverity_string_size_sink__(format);
+
+    ch = *format;
+    ch = *(char *)ap;
+
+    s = __coverity_alloc_nosize__();
+    __coverity_writeall__(s);
+    __coverity_mark_as_afm_allocated__(s, AFM_free);
+
+    return len;
+}
+
+char *g_strconcat(const char *s, ...)
+{
+    char *s;
+
+    /*
+     * Can't model: last argument must be null, the others
+     * null-terminated strings
+     */
+
+    s = __coverity_alloc_nosize__();
+    __coverity_writeall__(s);
+    __coverity_mark_as_afm_allocated__(s, AFM_free);
+    return s;
+}
+
 /* Other glib functions */
 
 typedef struct _GIOChannel GIOChannel;