gl_lcms: use thread-safe lcms API, require lcms2 2.6

The error log callback was not thread-safe and not library-safe. And
apparently there were some other details that made it not library-safe,
such as a global lcms plugin registry.

Switch the the thread-safe API provided by lcms2 starting with 2.6.
Remove our approximate thread-safety hacks.

Note that lcms basically provides 2 APIs now, the old functions, and
the thread-safe alternatives whose names end with THR. Some functions
don't change, because they already have a context of some sort. Care
must be taken not to accidentally use old APIs.

1 files changed, 16 insertions, 27 deletions

diff --git a/video/out/gl_lcms.c b/video/out/gl_lcms.c
index adda52b145..75388ada05 100644
--- a/video/out/gl_lcms.c
+++ b/video/out/gl_lcms.c
@@ -38,14 +38,8 @@
 
 #if HAVE_LCMS2
 
-#include <pthread.h>
 #include <lcms2.h>
 
-// lcms2 only provides a global error handler function, so we have to do this.
-// Not setting a lcms2 error handler will suppress any error messages.
-static pthread_mutex_t lcms2_dumb_crap_lock = PTHREAD_MUTEX_INITIALIZER;
-static struct mp_log *lcms2_dumb_crap;
-
 static bool parse_3dlut_size(const char *arg, int *p1, int *p2, int *p3)
 {
     if (sscanf(arg, "%dx%dx%d", p1, p2, p3) != 3)
@@ -87,10 +81,8 @@ const struct m_sub_options mp_icc_conf = {
 static void lcms2_error_handler(cmsContext ctx, cmsUInt32Number code,
                                 const char *msg)
 {
-    pthread_mutex_lock(&lcms2_dumb_crap_lock);
-    if (lcms2_dumb_crap)
-        mp_msg(lcms2_dumb_crap, MSGL_ERR, "lcms2: %s\n", msg);
-    pthread_mutex_unlock(&lcms2_dumb_crap_lock);
+    struct mp_log *log = cmsGetContextUserData(ctx);
+    mp_msg(log, MSGL_ERR, "lcms2: %s\n", msg);
 }
 
 static struct bstr load_file(void *talloc_ctx, const char *filename,
@@ -133,7 +125,7 @@ struct lut3d *mp_load_icc(struct mp_icc_opts *opts, struct mp_log *log,
     void *tmp = talloc_new(NULL);
     uint16_t *output = talloc_array(tmp, uint16_t, s_r * s_g * s_b * 3);
     struct lut3d *lut = NULL;
-    bool locked = false;
+    cmsContext cms = NULL;
 
     mp_msg(log, MSGL_INFO, "Opening ICC profile '%s'\n", opts->profile);
     struct bstr iccdata = load_file(tmp, opts->profile, global);
@@ -164,12 +156,12 @@ struct lut3d *mp_load_icc(struct mp_icc_opts *opts, struct mp_log *log,
         }
     }
 
-    locked = true;
-    pthread_mutex_lock(&lcms2_dumb_crap_lock);
-    lcms2_dumb_crap = log;
-    cmsSetLogErrorHandler(lcms2_error_handler);
+    cms = cmsCreateContext(NULL, log);
+    if (!cms)
+        goto error_exit;
+    cmsSetLogErrorHandlerTHR(cms, lcms2_error_handler);
 
-    cmsHPROFILE profile = cmsOpenProfileFromMem(iccdata.start, iccdata.len);
+    cmsHPROFILE profile = cmsOpenProfileFromMemTHR(cms, iccdata.start, iccdata.len);
     if (!profile)
         goto error_exit;
 
@@ -182,14 +174,14 @@ struct lut3d *mp_load_icc(struct mp_icc_opts *opts, struct mp_log *log,
 
     // 2.4 is arbitrarily used as a gamma compression factor for the 3DLUT,
     // reducing artifacts due to rounding errors on wide gamut profiles
-    cmsToneCurve *tonecurve = cmsBuildGamma(NULL, 2.4);
-    cmsHPROFILE vid_profile = cmsCreateRGBProfile(&d65, &bt709prim,
+    cmsToneCurve *tonecurve = cmsBuildGamma(cms, 2.4);
+    cmsHPROFILE vid_profile = cmsCreateRGBProfileTHR(cms, &d65, &bt709prim,
                         (cmsToneCurve*[3]){tonecurve, tonecurve, tonecurve});
     cmsFreeToneCurve(tonecurve);
-    cmsHTRANSFORM trafo = cmsCreateTransform(vid_profile, TYPE_RGB_16,
-                                             profile, TYPE_RGB_16,
-                                             opts->intent,
-                                             cmsFLAGS_HIGHRESPRECALC);
+    cmsHTRANSFORM trafo = cmsCreateTransformTHR(cms, vid_profile, TYPE_RGB_16,
+                                                profile, TYPE_RGB_16,
+                                                opts->intent,
+                                                cmsFLAGS_HIGHRESPRECALC);
     cmsCloseProfile(profile);
     cmsCloseProfile(vid_profile);
 
@@ -234,11 +226,8 @@ done: ;
 
 error_exit:
 
-    if (locked) {
-        lcms2_dumb_crap = NULL;
-        cmsSetLogErrorHandler(NULL);
-        pthread_mutex_unlock(&lcms2_dumb_crap_lock);
-    }
+    if (cms)
+        cmsDeleteContext(cms);
 
     if (!lut)
         mp_msg(log, MSGL_FATAL, "Error loading ICC profile.\n");