ext/opcache/zend_shared_alloc: make error_in strings const

This allows using string literals without implicitly casting away the
`const`.

Author: MaxKellermann

ext/opcache/shared_alloc_mmap.c

@@ -151,7 +151,7 @@ static void *find_prefered_mmap_base(size_t requested_size)
 }
 #endif
 
-static int create_segments(size_t requested_size, zend_shared_segment ***shared_segments_p, int *shared_segments_count, char **error_in)
+static int create_segments(size_t requested_size, zend_shared_segment ***shared_segments_p, int *shared_segments_count, const char **error_in)
 {
 #ifdef MADV_HUGEPAGE
 	/**

ext/opcache/shared_alloc_posix.c

@@ -36,7 +36,7 @@ typedef struct  {
     int shm_fd;
 } zend_shared_segment_posix;
 
-static int create_segments(size_t requested_size, zend_shared_segment_posix ***shared_segments_p, int *shared_segments_count, char **error_in)
+static int create_segments(size_t requested_size, zend_shared_segment_posix ***shared_segments_p, int *shared_segments_count, const char **error_in)
 {
 	zend_shared_segment_posix *shared_segment;
 	char shared_segment_name[sizeof("/ZendAccelerator.") + 20];

ext/opcache/shared_alloc_shm.c

@@ -50,7 +50,7 @@ typedef struct  {
     int shm_id;
 } zend_shared_segment_shm;
 
-static int create_segments(size_t requested_size, zend_shared_segment_shm ***shared_segments_p, int *shared_segments_count, char **error_in)
+static int create_segments(size_t requested_size, zend_shared_segment_shm ***shared_segments_p, int *shared_segments_count, const char **error_in)
 {
 	int i;
 	size_t allocate_size = 0, remaining_bytes = requested_size, seg_allocate_size;

ext/opcache/shared_alloc_win32.c

@@ -112,7 +112,7 @@ void zend_shared_alloc_unlock_win32(void)
 	ReleaseMutex(memory_mutex);
 }
 
-static int zend_shared_alloc_reattach(size_t requested_size, char **error_in)
+static int zend_shared_alloc_reattach(size_t requested_size, const char **error_in)
 {
 	int err;
 	void *wanted_mapping_base;
@@ -199,7 +199,7 @@ static int zend_shared_alloc_reattach(size_t requested_size, char **error_in)
 	return SUCCESSFULLY_REATTACHED;
 }
 
-static int create_segments(size_t requested_size, zend_shared_segment ***shared_segments_p, int *shared_segments_count, char **error_in)
+static int create_segments(size_t requested_size, zend_shared_segment ***shared_segments_p, int *shared_segments_count, const char **error_in)
 {
 	int err = 0, ret;
 	zend_shared_segment *shared_segment;

ext/opcache/zend_shared_alloc.c

@@ -132,7 +132,7 @@ void zend_shared_alloc_create_lock(char *lockfile_path)
 }
 #endif
 
-static void no_memory_bailout(size_t allocate_size, char *error)
+static void no_memory_bailout(size_t allocate_size, const char *error)
 {
 	zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Unable to allocate shared memory segment of %zu bytes: %s: %s (%d)", allocate_size, error?error:"unknown", strerror(errno), errno );
 }
@@ -152,7 +152,7 @@ static void copy_shared_segments(void *to, void *from, int count, int size)
 	}
 }
 
-static int zend_shared_alloc_try(const zend_shared_memory_handler_entry *he, size_t requested_size, zend_shared_segment ***shared_segments_p, int *shared_segments_count, char **error_in)
+static int zend_shared_alloc_try(const zend_shared_memory_handler_entry *he, size_t requested_size, zend_shared_segment ***shared_segments_p, int *shared_segments_count, const char **error_in)
 {
 	int res;
 	g_shared_alloc_handler = he->handler;
@@ -186,7 +186,7 @@ int zend_shared_alloc_startup(size_t requested_size, size_t reserved_size)
 	zend_shared_segment **tmp_shared_segments;
 	size_t shared_segments_array_size;
 	zend_smm_shared_globals tmp_shared_globals, *p_tmp_shared_globals;
-	char *error_in = NULL;
+	const char *error_in = NULL;
 	const zend_shared_memory_handler_entry *he;
 	int res = ALLOC_FAILURE;
 	int i;

ext/opcache/zend_shared_alloc.h

@@ -80,7 +80,7 @@ typedef struct _zend_shared_segment {
     void   *p;
 } zend_shared_segment;
 
-typedef int (*create_segments_t)(size_t requested_size, zend_shared_segment ***shared_segments, int *shared_segment_count, char **error_in);
+typedef int (*create_segments_t)(size_t requested_size, zend_shared_segment ***shared_segments, int *shared_segment_count, const char **error_in);
 typedef int (*detach_segment_t)(zend_shared_segment *shared_segment);
 
 typedef struct {