fe_memutils.h

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/*
 *  fe_memutils.h
 *      memory management support for frontend code
 *
 *  Copyright (c) 2003-2025, PostgreSQL Global Development Group
 *
 *  src/include/common/fe_memutils.h
 */
#ifndef FE_MEMUTILS_H
#define FE_MEMUTILS_H
 
/*
 * Assumed maximum size for allocation requests.
 *
 * We don't enforce this, so the actual maximum is the platform's SIZE_MAX.
 * But it's useful to have it defined in frontend builds, so that common
 * code can check for oversized requests without having frontend-vs-backend
 * differences.  Also, some code relies on MaxAllocSize being no more than
 * INT_MAX/2, so rather than setting this to SIZE_MAX, make it the same as
 * the backend's value.
 */
#define MaxAllocSize    ((Size) 0x3fffffff) /* 1 gigabyte - 1 */
 
/*
 * Flags for pg_malloc_extended and palloc_extended, deliberately named
 * the same as the backend flags.
 */
#define MCXT_ALLOC_HUGE         0x01    /* allow huge allocation (> 1 GB) not
                                         * actually used for frontends */
#define MCXT_ALLOC_NO_OOM       0x02    /* no failure if out-of-memory */
#define MCXT_ALLOC_ZERO         0x04    /* zero allocated memory */
 
/*
 * "Safe" memory allocation functions --- these exit(1) on failure
 * (except pg_malloc_extended with MCXT_ALLOC_NO_OOM)
 */
extern char *pg_strdup(const char *in);
extern void *pg_malloc(size_t size);
extern void *pg_malloc0(size_t size);
extern void *pg_malloc_extended(size_t size, int flags);
extern void *pg_realloc(void *ptr, size_t size);
extern void pg_free(void *ptr);
 
/*
 * Variants with easier notation and more type safety
 */
 
/*
 * Allocate space for one object of type "type"
 */
#define pg_malloc_object(type) ((type *) pg_malloc(sizeof(type)))
#define pg_malloc0_object(type) ((type *) pg_malloc0(sizeof(type)))
 
/*
 * Allocate space for "count" objects of type "type"
 */
#define pg_malloc_array(type, count) ((type *) pg_malloc(sizeof(type) * (count)))
#define pg_malloc0_array(type, count) ((type *) pg_malloc0(sizeof(type) * (count)))
 
/*
 * Change size of allocation pointed to by "pointer" to have space for "count"
 * objects of type "type"
 */
#define pg_realloc_array(pointer, type, count) ((type *) pg_realloc(pointer, sizeof(type) * (count)))
 
/* Equivalent functions, deliberately named the same as backend functions */
extern char *pstrdup(const char *in);
extern char *pnstrdup(const char *in, Size size);
extern void *palloc(Size size);
extern void *palloc0(Size size);
extern void *palloc_extended(Size size, int flags);
extern void *repalloc(void *pointer, Size size);
extern void pfree(void *pointer);
 
#define palloc_object(type) ((type *) palloc(sizeof(type)))
#define palloc0_object(type) ((type *) palloc0(sizeof(type)))
#define palloc_array(type, count) ((type *) palloc(sizeof(type) * (count)))
#define palloc0_array(type, count) ((type *) palloc0(sizeof(type) * (count)))
#define repalloc_array(pointer, type, count) ((type *) repalloc(pointer, sizeof(type) * (count)))
 
/* sprintf into a palloc'd buffer --- these are in psprintf.c */
extern char *psprintf(const char *fmt,...) pg_attribute_printf(1, 2);
extern size_t pvsnprintf(char *buf, size_t len, const char *fmt, va_list args) pg_attribute_printf(3, 0);
 
#endif                          /* FE_MEMUTILS_H */