// SPDX-License-Identifier: GPL-2.0#include "comm.h"#include <errno.h>#include <string.h>#include <internal/rc_check.h>#include <linux/refcount.h>#include <linux/zalloc.h>#include <tools/libc_compat.h> // reallocarray #include "rwsem.h" DECLARE_RC_STRUCT(comm_str) {	refcount_t refcnt;	char str[];}; static struct comm_strs {	struct rw_semaphore lock;	struct comm_str **strs;	int num_strs;	int capacity;} _comm_strs; static void comm_strs__remove_if_last(struct comm_str *cs); static void comm_strs__init(void)	NO_THREAD_SAFETY_ANALYSIS /* Inherently single threaded due to pthread_once. */{	init_rwsem(&_comm_strs.lock);	_comm_strs.capacity = 16;	_comm_strs.num_strs = 0;	_comm_strs.strs = calloc(16, sizeof(*_comm_strs.strs));} static struct comm_strs *comm_strs__get(void){	static pthread_once_t comm_strs_type_once = PTHREAD_ONCE_INIT; 	pthread_once(&comm_strs_type_once, comm_strs__init); 	return &_comm_strs;} static refcount_t *comm_str__refcnt(struct comm_str *cs){	return &RC_CHK_ACCESS(cs)->refcnt;} static const char *comm_str__str(const struct comm_str *cs){	return &RC_CHK_ACCESS(cs)->str[0];} static struct comm_str *comm_str__get(struct comm_str *cs){	struct comm_str *result; 	if (RC_CHK_GET(result, cs))		refcount_inc_not_zero(comm_str__refcnt(cs)); 	return result;} static void comm_str__put(struct comm_str *cs){	if (!cs)		return; 	if (refcount_dec_and_test(comm_str__refcnt(cs))) {		RC_CHK_FREE(cs);	} else {		if (refcount_read(comm_str__refcnt(cs)) == 1)			comm_strs__remove_if_last(cs); 		RC_CHK_PUT(cs);	}} static struct comm_str *comm_str__new(const char *str){	struct comm_str *result = NULL;	RC_STRUCT(comm_str) *cs; 	cs = malloc(sizeof(*cs) + strlen(str) + 1);	if (ADD_RC_CHK(result, cs)) {		refcount_set(comm_str__refcnt(result), 1);		strcpy(&cs->str[0], str);	}	return result;} static int comm_str__search(const void *_key, const void *_member){	const char *key = _key;	const struct comm_str *member = *(const struct comm_str * const *)_member; 	return strcmp(key, comm_str__str(member));} static void comm_strs__remove_if_last(struct comm_str *cs){	struct comm_strs *comm_strs = comm_strs__get(); 	down_write(&comm_strs->lock);	/*	 * Are there only references from the array, if so remove the array	 * reference under the write lock so that we don't race with findnew.	 */	if (refcount_read(comm_str__refcnt(cs)) == 1) {		struct comm_str **entry; 		entry = bsearch(comm_str__str(cs), comm_strs->strs, comm_strs->num_strs,				sizeof(struct comm_str *), comm_str__search);		comm_str__put(*entry);		for (int i = entry - comm_strs->strs; i < comm_strs->num_strs - 1; i++)			comm_strs->strs[i] = comm_strs->strs[i + 1];		comm_strs->num_strs--;	}	up_write(&comm_strs->lock);} static struct comm_str *__comm_strs__find(struct comm_strs *comm_strs, const char *str)	SHARED_LOCKS_REQUIRED(comm_strs->lock){	struct comm_str **result; 	result = bsearch(str, comm_strs->strs, comm_strs->num_strs, sizeof(struct comm_str *),			 comm_str__search); 	if (!result)		return NULL; 	return comm_str__get(*result);} static struct comm_str *comm_strs__findnew(const char *str){	struct comm_strs *comm_strs = comm_strs__get();	struct comm_str *result; 	if (!comm_strs)		return NULL; 	down_read(&comm_strs->lock);	result = __comm_strs__find(comm_strs, str);	up_read(&comm_strs->lock);	if (result)		return result; 	down_write(&comm_strs->lock);	result = __comm_strs__find(comm_strs, str);	if (!result) {		if (comm_strs->num_strs == comm_strs->capacity) {			struct comm_str **tmp; 			tmp = reallocarray(comm_strs->strs,					   comm_strs->capacity + 16,					   sizeof(*comm_strs->strs));			if (!tmp) {				up_write(&comm_strs->lock);				return NULL;			}			comm_strs->strs = tmp;			comm_strs->capacity += 16;		}		result = comm_str__new(str);		if (result) {			int low = 0, high = comm_strs->num_strs - 1;			int insert = comm_strs->num_strs; /* Default to inserting at the end. */ 			while (low <= high) {				int mid = low + (high - low) / 2;				int cmp = strcmp(comm_str__str(comm_strs->strs[mid]), str); 				if (cmp < 0) {					low = mid + 1;				} else {					high = mid - 1;					insert = mid;				}			}			memmove(&comm_strs->strs[insert + 1], &comm_strs->strs[insert],				(comm_strs->num_strs - insert) * sizeof(struct comm_str *));			comm_strs->num_strs++;			comm_strs->strs[insert] = result;		}	}	up_write(&comm_strs->lock);	return comm_str__get(result);} struct comm *comm__new(const char *str, u64 timestamp, bool exec){	struct comm *comm = zalloc(sizeof(*comm)); 	if (!comm)		return NULL; 	comm->start = timestamp;	comm->exec = exec; 	comm->comm_str = comm_strs__findnew(str);	if (!comm->comm_str) {		free(comm);		return NULL;	} 	return comm;} int comm__override(struct comm *comm, const char *str, u64 timestamp, bool exec){	struct comm_str *new, *old = comm->comm_str; 	new = comm_strs__findnew(str);	if (!new)		return -ENOMEM; 	comm_str__put(old);	comm->comm_str = new;	comm->start = timestamp;	if (exec)		comm->exec = true; 	return 0;} void comm__free(struct comm *comm){	comm_str__put(comm->comm_str);	free(comm);} const char *comm__str(const struct comm *comm){	return comm_str__str(comm->comm_str);}