libavutil: Deprecate av_fopen_utf8, provide an avpriv version

Since every DLL can use an individual CRT on Windows, having
an exported function that opens a FILE* won't work if that
FILE* is going to be used from a different DLL (or from user
application code).

Internally within the libraries, the issue can be worked around
by duplicating the function in all libraries (this already happened
implicitly because the function resided in file_open.c) and renaming
the function to ff_fopen_utf8 (so that it doesn't end up exported from
the DLLs) and duplicating it in all libraries that use it.

This makes the avpriv_fopen_utf8 / ff_fopen_utf8 function work in
the exact same way as the existing avpriv_open / ff_open, with the
same setup as introduced in e743e7ae6e.

That mechanism doesn't work for external users, thus deprecate the
existing function.

Signed-off-by: Martin Storsjö <martin@martin.st>

doc/APIchanges

@@ -14,6 +14,9 @@ libavutil:     2021-04-27
 
 API changes, most recent first:
 
+2022-05-23 - xxxxxxxxx - lavu 57.25.100 - avutil.h
+  Deprecate av_fopen_utf8() without replacement.
+
 2022-03-16 - xxxxxxxxxx - all libraries - version_major.h
   Add lib<name>/version_major.h as new installed headers, which only
   contain the major version number (and corresponding API deprecation

fftools/fopen_utf8.h

@@ -21,7 +21,7 @@
 
 #include <stdio.h>
 
-/* The fopen_utf8 function here is essentially equivalent to av_fopen_utf8,
+/* The fopen_utf8 function here is essentially equivalent to avpriv_fopen_utf8,
  * except that it doesn't set O_CLOEXEC, and that it isn't exported
  * from a different library. (On Windows, each DLL might use a different
  * CRT, and FILE* handles can't be shared across them.) */

libavfilter/Makefile

@@ -23,6 +23,7 @@ OBJS = allfilters.o                                                     \
        version.o                                                        \
        video.o                                                          \
 
+OBJS-$(HAVE_LIBC_MSVCRT)                     += file_open.o
 OBJS-$(HAVE_THREADS)                         += pthread.o
 
 # subsystems

libavfilter/file_open.c

@@ -0,0 +1 @@
+#include "libavutil/file_open.c"

libavutil/avutil.h

@@ -331,12 +331,18 @@ unsigned av_int_list_length_for_size(unsigned elsize,
 #define av_int_list_length(list, term) \
     av_int_list_length_for_size(sizeof(*(list)), list, term)
 
+#if FF_API_AV_FOPEN_UTF8
 /**
  * Open a file using a UTF-8 filename.
  * The API of this function matches POSIX fopen(), errors are returned through
  * errno.
+ * @deprecated Avoid using it, as on Windows, the FILE* allocated by this
+ *             function may be allocated with a different CRT than the caller
+ *             who uses the FILE*. No replacement provided in public API.
  */
+attribute_deprecated
 FILE *av_fopen_utf8(const char *path, const char *mode);
+#endif
 
 /**
  * Return the fractional representation of the internal time base.

libavutil/file_open.c

@@ -155,7 +155,7 @@ int avpriv_tempfile(const char *prefix, char **filename, int log_offset, void *l
     return fd; /* success */
 }
 
-FILE *av_fopen_utf8(const char *path, const char *mode)
+FILE *avpriv_fopen_utf8(const char *path, const char *mode)
 {
     int fd;
     int access;
@@ -188,3 +188,10 @@ FILE *av_fopen_utf8(const char *path, const char *mode)
         return NULL;
     return fdopen(fd, mode);
 }
+
+#if FF_API_AV_FOPEN_UTF8
+FILE *av_fopen_utf8(const char *path, const char *mode)
+{
+    return avpriv_fopen_utf8(path, mode);
+}
+#endif

libavutil/internal.h

@@ -37,6 +37,7 @@
 #include <stdint.h>
 #include <stddef.h>
 #include <assert.h>
+#include <stdio.h>
 #include "config.h"
 #include "attributes.h"
 #include "timer.h"
@@ -183,8 +184,10 @@ void avpriv_request_sample(void *avc,
 #pragma comment(linker, "/include:" EXTERN_PREFIX "avpriv_snprintf")
 #endif
 
+#define avpriv_fopen_utf8 ff_fopen_utf8
 #define avpriv_open ff_open
 #define avpriv_tempfile ff_tempfile
+
 #define PTRDIFF_SPECIFIER "Id"
 #define SIZE_SPECIFIER "Iu"
 #else
@@ -256,6 +259,11 @@ static av_always_inline av_const int64_t ff_rint64_clip(double a, int64_t amin,
 av_warn_unused_result
 int avpriv_open(const char *filename, int flags, ...);
 
+/**
+ * Open a file using a UTF-8 filename.
+ */
+FILE *avpriv_fopen_utf8(const char *path, const char *mode);
+
 /**
  * Wrapper to work around the lack of mkstemp() on mingw.
  * Also, tries to create file in /tmp first, if possible.

libavutil/version.h

@@ -79,8 +79,8 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  57
-#define LIBAVUTIL_VERSION_MINOR  24
-#define LIBAVUTIL_VERSION_MICRO 101
+#define LIBAVUTIL_VERSION_MINOR  25
+#define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
                                                LIBAVUTIL_VERSION_MINOR, \
@@ -113,6 +113,7 @@
 #define FF_API_FIFO_OLD_API             (LIBAVUTIL_VERSION_MAJOR < 58)
 #define FF_API_XVMC                     (LIBAVUTIL_VERSION_MAJOR < 58)
 #define FF_API_OLD_CHANNEL_LAYOUT       (LIBAVUTIL_VERSION_MAJOR < 58)
+#define FF_API_AV_FOPEN_UTF8            (LIBAVUTIL_VERSION_MAJOR < 58)
 
 /**
  * @}

tests/ref/fate/source

@@ -8,6 +8,7 @@ libavcodec/reverse.c
 libavdevice/file_open.c
 libavdevice/reverse.c
 libavfilter/af_arnndn.c
+libavfilter/file_open.c
 libavfilter/log2_tab.c
 libavformat/file_open.c
 libavformat/golomb_tab.c