Import Upstream version 1.8.5

[hcoop/debian/openafs.git] / src / afsweb / apache_includes / 1.2 / alloc.h

/* ====================================================================
 * Copyright (c) 1995-1997 The Apache Group.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
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 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the Apache Group
 *    for use in the Apache HTTP server project (http://www.apache.org/)."
 *
 * 4. The names "Apache Server" and "Apache Group" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 5. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the Apache Group
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 *
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Group and was originally based
 * on public domain software written at the National Center for
 * Supercomputing Applications, University of Illinois, Urbana-Champaign.
 * For more information on the Apache Group and the Apache HTTP server
 * project, please see <http://www.apache.org/>.
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 */

/*
 * Resource allocation routines...
 *
 * designed so that we don't have to keep track of EVERYTHING so that
 * it can be explicitly freed later (a fundamentally unsound strategy ---
 * particularly in the presence of die()).
 *
 * Instead, we maintain pools, and allocate items (both memory and I/O
 * handlers) from the pools --- currently there are two, one for per
 * transaction info, and one for config info.  When a transaction is over,
 * we can delete everything in the per-transaction pool without fear, and
 * without thinking too hard about it either.
 *
 * rst
 */

/* Arenas for configuration info and transaction info
 * --- actual layout of the pool structure is private to 
 * alloc.c.  
 */

typedef struct pool pool;

extern pool *permanent_pool;
void init_alloc();		/* Set up everything */
pool *make_sub_pool(pool *);	/* All pools are subpools of permanent_pool */
void destroy_pool(pool *);

/* Clearing out EVERYTHING in an pool... destroys any sub-pools */

void clear_pool(struct pool *);

/* Preparing for exec() --- close files, etc., but *don't* flush I/O
 * buffers, *don't* wait for subprocesses, and *don't* free any memory.
 */

void cleanup_for_exec();

/* routines to allocate memory from an pool... */

void *palloc(struct pool *, int nbytes);
void *pcalloc(struct pool *, int nbytes);
extern char *pstrdup(struct pool *, const char *s);
extern char *pstrndup(struct pool *, const char *s, int n);
char *pstrcat(struct pool *, ...);	/* all '...' must be char* */

/* array and alist management... keeping lists of things.
 * Common enough to want common support code ...
 */

typedef struct {
    pool *pool;
    int elt_size;
    int nelts;
    int nalloc;
    char *elts;
} array_header;

array_header *make_array(pool * p, int nelts, int elt_size);
void *push_array(array_header *);
void array_cat(array_header * dst, const array_header * src);
array_header *append_arrays(pool *, const array_header *,
			    const array_header *);

/* copy_array copies the *entire* array.  copy_array_hdr just copies
 * the header, and arranges for the elements to be copied if (and only
 * if) the code subsequently does a push or arraycat.
 */

array_header *copy_array(pool * p, const array_header * src);
array_header *copy_array_hdr(pool * p, const array_header * src);


/* Tables.  Implemented alist style, for now, though we try to keep
 * it so that imposing a hash table structure on top in the future
 * wouldn't be *too* hard...
 *
 * Note that key comparisons for these are case-insensitive, largely
 * because that's what's appropriate and convenient everywhere they're
 * currently being used...
 */

typedef array_header table;

typedef struct {
    char *key;			/* maybe NULL in future;
				 * check when iterating thru table_elts
				 */
    char *val;
} table_entry;

table *make_table(pool * p, int nelts);
table *copy_table(pool * p, const table *);
void clear_table(table *);
char *table_get(const table *, const char *);
void table_set(table *, const char *name, const char *val);
void table_merge(table *, const char *name, const char *more_val);
void table_unset(table *, const char *key);
void table_add(table *, const char *name, const char *val);
void table_do(int (*comp) (void *, const char *, const char *), void *rec,
	      const table * t, ...);

table *overlay_tables(pool * p, const table * overlay, const table * base);

array_header *table_elts(table *);

#define is_empty_table(t) (((t) == NULL)||((t)->nelts == 0))

/* routines to remember allocation of other sorts of things...
 * generic interface first.  Note that we want to have two separate
 * cleanup functions in the general case, one for exec() preparation,
 * to keep CGI scripts and the like from inheriting access to things
 * they shouldn't be able to touch, and one for actually cleaning up,
 * when the actual server process wants to get rid of the thing,
 * whatever it is.  
 *
 * kill_cleanup disarms a cleanup, presumably because the resource in
 * question has been closed, freed, or whatever, and it's scarce
 * enough to want to reclaim (e.g., descriptors).  It arranges for the
 * resource not to be cleaned up a second time (it might have been
 * reallocated).  run_cleanup does the same, but runs it first.
 *
 * Cleanups are identified for purposes of finding & running them off by the
 * plain_cleanup and data, which should presumably be unique.
 *
 * NB any code which invokes register_cleanup or kill_cleanup directly
 * is a critical section which should be guarded by block_alarms() and
 * unblock_alarms() below...
 */

void register_cleanup(pool * p, void *data, void (*plain_cleanup) (void *),
		      void (*child_cleanup) (void *));

void kill_cleanup(pool * p, void *data, void (*plain_cleanup) (void *));
void run_cleanup(pool * p, void *data, void (*cleanup) (void *));

/* The time between when a resource is actually allocated, and when it
 * its cleanup is registered is a critical section, during which the
 * resource could leak if we got interrupted or timed out.  So, anything
 * which registers cleanups should bracket resource allocation and the
 * cleanup registry with these.  (This is done internally by run_cleanup).
 *
 * NB they are actually implemented in http_main.c, since they are bound
 * up with timeout handling in general...
 */

extern void block_alarms();
extern void unblock_alarms();

/* Common cases which want utility support..
 * the note_cleanups_for_foo routines are for 
 */

FILE *pfopen(struct pool *, const char *name, const char *fmode);
FILE *pfdopen(struct pool *, int fd, const char *fmode);
int popenf(struct pool *, const char *name, int flg, int mode);

void note_cleanups_for_file(pool *, FILE *);
void note_cleanups_for_fd(pool *, int);
void kill_cleanups_for_fd(pool * p, int fd);

regex_t *pregcomp(pool * p, const char *pattern, int cflags);
void pregfree(pool * p, regex_t * reg);

/* routines to note closes... file descriptors are constrained enough
 * on some systems that we want to support this.
 */

int pfclose(struct pool *, FILE *);
int pclosef(struct pool *, int fd);

/* ... even child processes (which we may want to wait for,
 * or to kill outright, on unexpected termination).
 *
 * spawn_child is a utility routine which handles an awful lot of
 * the rigamarole associated with spawning a child --- it arranges
 * for pipes to the child's stdin and stdout, if desired (if not,
 * set the associated args to NULL).  It takes as args a function
 * to call in the child, and an argument to be passed to the function.
 */

enum kill_conditions { kill_never, kill_always, kill_after_timeout,
    just_wait
};

int spawn_child_err(pool *, void (*)(void *), void *, enum kill_conditions,
		    FILE ** pipe_in, FILE ** pipe_out, FILE ** pipe_err);
#define spawn_child(p,f,v,k,in,out) spawn_child_err(p,f,v,k,in,out,NULL)

/* magic numbers --- min free bytes to consider a free pool block useable,
 * and the min amount to allocate if we have to go to malloc() */

#define BLOCK_MINFREE 4096
#define BLOCK_MINALLOC 8192

/* Finally, some accounting */

long bytes_in_pool(pool * p);
long bytes_in_free_blocks();