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shared: add nm_vsprintf_buf_or_alloc() macro

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Thomas Haller 2021-01-14 11:43:39 +01:00
parent 098ac7dbc0
commit 45ba49f322
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GPG key ID: 29C2366E4DFC5728
1 changed files with 48 additions and 0 deletions
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48
src/libnm-glib-aux/nm-macros-internal.h
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@ -1733,6 +1733,54 @@ nm_decode_version(guint version, guint *major, guint *minor, guint *micro)
_buf; \
})
#define nm_vsprintf_buf_or_alloc(format, va_last_arg, sbuf_stack, out_sbuf_heap, out_len) \
({ \
const char *const _format = (format); \
char *const _sbuf_stack = (sbuf_stack); \
char **const _out_sbuf_heap = (out_sbuf_heap); \
gsize *const _out_len = (out_len); \
const char * _msg; \
va_list _va_args; \
int _l; \
\
G_STATIC_ASSERT_EXPR(G_N_ELEMENTS(sbuf_stack) > sizeof(_sbuf_stack)); \
\
va_start(_va_args, va_last_arg); \
_l = g_vsnprintf(_sbuf_stack, sizeof(sbuf_stack), _format, _va_args); \
va_end(_va_args); \
\
nm_assert(_l >= 0 && _l < G_MAXINT); \
\
if ((gsize) _l >= sizeof(sbuf_stack)) { \
const gsize _l2 = ((gsize) _l) + 1u; \
char * _sbuf_heap; \
\
/* Don't use g_strdup_vprintf() here either, because that also needs
* to first determine the length (which is commonly does by printing
* to a stack allocated buffer of size 1. We already know the required
* size. */ \
\
_sbuf_heap = g_malloc(_l2); \
\
va_start(_va_args, va_last_arg); \
_l = g_vsnprintf(_sbuf_heap, _l2, _format, _va_args); \
va_end(_va_args); \
\
nm_assert(_l >= 0 && ((gsize) _l) == _l2 - 1u); \
\
_msg = _sbuf_heap; \
*_out_sbuf_heap = _sbuf_heap; \
} else { \
_msg = _sbuf_stack; \
*_out_sbuf_heap = NULL; \
} \
\
nm_assert(strlen(_msg) == (gsize) _l); \
NM_SET_OUT(_out_len, (gsize) _l); \
\
_msg; \
})
/* it is "unsafe" because @bufsize must not be a constant expression and
* there is no check at compiletime. Regardless of that, the buffer size
* must not be larger than 300 bytes, as this gets stack allocated. */