From fcf3f124d626afbc2438756efb7605a4324eb94d Mon Sep 17 00:00:00 2001
From: Jan Beich <jbeich@FreeBSD.org>
Date: Tue, 19 Jan 2021 14:20:55 +0000
Subject: [PATCH] shm: unbreak build without memfd_create

New FreeBSD versions have memfd_create but other BSDs don't.

pgo/pgo.c:260:22: error: implicit declaration of function 'memfd_create' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        int mem_fd = memfd_create("foot-pgo-ptmx", MFD_CLOEXEC);
                     ^
pgo/pgo.c:260:52: error: use of undeclared identifier 'MFD_CLOEXEC'
        int mem_fd = memfd_create("foot-pgo-ptmx", MFD_CLOEXEC);
                                                   ^
shm.c:13:10: fatal error: 'linux/mman.h' file not found
 #include <linux/mman.h>
          ^~~~~~~~~~~~~~
shm.c:277:15: error: implicit declaration of function 'memfd_create' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
    pool_fd = memfd_create("foot-wayland-shm-buffer-pool", MFD_CLOEXEC | MFD_ALLOW_SEALING);
              ^
shm.c:277:60: error: use of undeclared identifier 'MFD_CLOEXEC'
    pool_fd = memfd_create("foot-wayland-shm-buffer-pool", MFD_CLOEXEC | MFD_ALLOW_SEALING);
                                                           ^
shm.c:277:74: error: use of undeclared identifier 'MFD_ALLOW_SEALING'
    pool_fd = memfd_create("foot-wayland-shm-buffer-pool", MFD_CLOEXEC | MFD_ALLOW_SEALING);
                                                                         ^
shm.c:339:15: error: use of undeclared identifier 'F_SEAL_GROW'
              F_SEAL_GROW | F_SEAL_SHRINK | /*F_SEAL_FUTURE_WRITE |*/ F_SEAL_SEAL) < 0)
              ^
shm.c:339:29: error: use of undeclared identifier 'F_SEAL_SHRINK'
              F_SEAL_GROW | F_SEAL_SHRINK | /*F_SEAL_FUTURE_WRITE |*/ F_SEAL_SEAL) < 0)
                            ^
shm.c:339:71: error: use of undeclared identifier 'F_SEAL_SEAL'
              F_SEAL_GROW | F_SEAL_SHRINK | /*F_SEAL_FUTURE_WRITE |*/ F_SEAL_SEAL) < 0)
                                                                      ^
shm.c:338:24: error: use of undeclared identifier 'F_ADD_SEALS'
    if (fcntl(pool_fd, F_ADD_SEALS,
                       ^
---
 meson.build |  4 ++++
 pgo/pgo.c   |  9 +++++++++
 shm.c       | 14 ++++++++++++--
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/meson.build b/meson.build
index de159204..e1b9eb51 100644
--- a/meson.build
+++ b/meson.build
@@ -12,6 +12,10 @@ is_debug_build = get_option('buildtype').startswith('debug')
 
 cc = meson.get_compiler('c')
 
+if cc.has_function('memfd_create')
+  add_project_arguments('-DMEMFD_CREATE', language: 'c')
+endif
+
 add_project_arguments(
   ['-D_POSIX_C_SOURCE=200809L', '-D_GNU_SOURCE=200809L'] +
   (is_debug_build
diff --git a/pgo/pgo.c b/pgo/pgo.c
index 39c20de0..fa95a0ec 100644
--- a/pgo/pgo.c
+++ b/pgo/pgo.c
@@ -257,7 +257,16 @@ main(int argc, const char *const *argv)
 
         close(fd);
 
+#if defined(MEMFD_CREATE)
         int mem_fd = memfd_create("foot-pgo-ptmx", MFD_CLOEXEC);
+#elif defined(__FreeBSD__)
+        // memfd_create on FreeBSD 13 is SHM_ANON without sealing support
+        int mem_fd = shm_open(SHM_ANON, O_RDWR | O_CLOEXEC, 0600);
+#else
+        char name[] = "/tmp/foot-pgo-ptmx-XXXXXX";
+        int mem_fd = mkostemp(name, O_CLOEXEC);
+        unlink(name);
+#endif
         if (mem_fd < 0) {
             fprintf(stderr, "error: failed to create memory FD\n");
             goto out;
diff --git a/shm.c b/shm.c
index 81de653b..85d67f9c 100644
--- a/shm.c
+++ b/shm.c
@@ -10,8 +10,7 @@
 #include <sys/types.h>
 #include <sys/mman.h>
 #include <sys/time.h>
-#include <linux/mman.h>
-#include <linux/memfd.h>
+#include <sys/mman.h>
 #include <fcntl.h>
 
 #include <pixman.h>
@@ -276,7 +275,16 @@ shm_get_buffer(struct wl_shm *shm, int width, int height, unsigned long cookie,
     LOG_DBG("cookie=%lx: allocating new buffer: %zu KB", cookie, size / 1024);
 
     /* Backing memory for SHM */
+#if defined(MEMFD_CREATE)
     pool_fd = memfd_create("foot-wayland-shm-buffer-pool", MFD_CLOEXEC | MFD_ALLOW_SEALING);
+#elif defined(__FreeBSD__)
+    // memfd_create on FreeBSD 13 is SHM_ANON without sealing support
+    pool_fd = shm_open(SHM_ANON, O_RDWR | O_CLOEXEC, 0600);
+#else
+    char name[] = "/tmp/foot-wayland-shm-buffer-pool-XXXXXX";
+    pool_fd = mkostemp(name, O_CLOEXEC);
+    unlink(name);
+#endif
     if (pool_fd == -1) {
         LOG_ERRNO("failed to create SHM backing memory file");
         goto err;
@@ -335,6 +343,7 @@ shm_get_buffer(struct wl_shm *shm, int width, int height, unsigned long cookie,
         goto err;
     }
 
+#if defined(MEMFD_CREATE)
     /* Seal file - we no longer allow any kind of resizing */
     /* TODO: wayland mmaps(PROT_WRITE), for some unknown reason, hence we cannot use F_SEAL_FUTURE_WRITE */
     if (fcntl(pool_fd, F_ADD_SEALS,
@@ -343,6 +352,7 @@ shm_get_buffer(struct wl_shm *shm, int width, int height, unsigned long cookie,
         LOG_ERRNO("failed to seal SHM backing memory file");
         /* This is not a fatal error */
     }
+#endif
 
     pool = wl_shm_create_pool(shm, pool_fd, memfd_size);
     if (pool == NULL) {