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greg |
2.1 |
#ifndef lint
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greg |
2.4 |
static const char RCSid[] = "$Id: RdataShareMap.cpp,v 2.3 2024/10/31 23:55:04 greg Exp $";
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greg |
2.1 |
#endif
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/*
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* RdataShareMap.cpp
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*
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* Shared data using memory-mapped file
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*
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* Created by Greg Ward on 10/14/2024
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*/
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#include "rtio.h"
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#include "rterror.h"
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#include "RdataShare.h"
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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// Create memory-mapped file object
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RdataShareMap::RdataShareMap(const char *name, int flags, size_t siz)
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{
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mmorg = NULL;
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bufCount = 0;
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if (!(flags & (RDSread|RDSwrite))) {
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error(CONSISTENCY, "RdataShareMap() flags must include RDSread or RDSwrite");
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return;
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}
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if (name && !*name) name = NULL;
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if (!name && !siz | ((flags & (RDSextend|RDSread|RDSwrite)) !=
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(RDSextend|RDSread|RDSwrite))) {
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error(CONSISTENCY, "anonymous memory map must be read/write");
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return;
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}
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if ((flags & (RDSextend|RDSwrite)) == RDSextend) {
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error(CONSISTENCY, "bad RDSextend in RdataShareMap()");
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return;
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}
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greg |
2.2 |
int oflags, mmprot;
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greg |
2.1 |
switch (flags & (RDSread|RDSwrite)) {
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case RDSread|RDSwrite:
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greg |
2.2 |
mmprot = PROT_READ|PROT_WRITE;
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oflags = O_RDWR|O_CREAT;
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break;
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case RDSwrite:
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mmprot = PROT_WRITE;
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oflags = O_RDWR|O_CREAT; // XXX system limitation
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greg |
2.1 |
break;
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case RDSread:
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greg |
2.2 |
mmprot = PROT_READ;
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oflags = O_RDONLY;
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greg |
2.1 |
break;
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}
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int fd = -1;
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if (name) { // opening a shared file
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greg |
2.2 |
if (flags & RDSexcl) oflags |= O_EXCL;
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greg |
2.1 |
else if (flags & RDSextend && !siz) oflags |= O_TRUNC;
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fd = open(name, oflags, 0666);
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if (fd < 0) {
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sprintf(errmsg, "cannot open '%s'", name);
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error(SYSTEM, errmsg);
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return;
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}
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if (!(flags & RDSextend)) {
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struct stat sbuf;
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if (flags & RDSexcl)
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siz = 0;
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else if (fstat(fd, &sbuf) >= 0)
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siz = sbuf.st_size;
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else {
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greg |
2.4 |
sprintf(errmsg, "cannot stat '%s'", name);
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greg |
2.1 |
error(SYSTEM, errmsg);
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close(fd);
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return;
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}
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} else if (siz && ftruncate(fd, siz) < 0) {
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sprintf(errmsg, "cannot resize '%s'", name);
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error(SYSTEM, errmsg);
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close(fd);
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return;
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}
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}
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greg |
2.3 |
if (siz) mmorg = (void *)mmap(NULL, siz, mmprot,
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greg |
2.1 |
MAP_SHARED|(name ? MAP_FILE : MAP_ANON), fd, 0);
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close(fd);
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if (mmorg == MAP_FAILED) {
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if (name)
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sprintf(errmsg, "cannot map '%s' to memory", name);
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else
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sprintf(errmsg, "cannot map anonymous map of %ld KBytes",
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long(siz/1024));
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error(SYSTEM, errmsg);
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mmorg = NULL;
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return;
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}
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osiz = siz;
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if (name) chName = savqstr(name);
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mode = flags;
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}
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RdataShareMap::~RdataShareMap()
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{
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if (mmorg) munmap(mmorg, osiz);
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}
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// Attempt to extend or shrink object (adjust if 0)
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size_t
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RdataShareMap::Resize(size_t new_siz)
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{
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if (new_siz > 0) {
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if (new_siz == osiz)
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return osiz;
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if (!(mode & RDSwrite)) {
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error(CONSISTENCY, "cannot resize read-only map");
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return 0;
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}
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}
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if (bufCount > 0) {
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error(INTERNAL, "cannot resize while memory is checked out");
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return 0;
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}
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if (!chName) {
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if (!new_siz) // XXX should issue warning?
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return osiz;
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if (new_siz > osiz) {
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error(INTERNAL, "cannot grow anonymous map");
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return 0;
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}
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return osiz = new_siz; // just pretend we shrank
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}
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if (!new_siz) { // sync to current file length?
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struct stat sbuf;
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if (stat(chName, &sbuf) < 0) {
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sprintf(errmsg, "cannot stat '%s'", chName);
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error(SYSTEM, errmsg);
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return 0;
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}
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if (sbuf.st_size <= osiz)
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return osiz = sbuf.st_size;
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new_siz = sbuf.st_size;
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}
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if (new_siz > osiz) { // need to extend & remap
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int fd = open(chName, mode&RDSread ? O_RDWR : O_WRONLY);
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if (fd < 0) {
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sprintf(errmsg, "cannot reopen '%s'", chName);
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error(SYSTEM, errmsg);
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return 0;
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}
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if (ftruncate(fd, new_siz) < 0) {
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sprintf(errmsg, "cannot grow '%s'", chName);
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error(SYSTEM, errmsg);
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close(fd);
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return 0;
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}
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greg |
2.3 |
if (mmorg) munmap(mmorg, osiz);
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greg |
2.1 |
mmorg = mmap(NULL, new_siz,
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mode&RDSread ? PROT_READ|PROT_WRITE : PROT_WRITE,
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MAP_SHARED|MAP_FILE, fd, 0);
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close(fd);
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if (mmorg == MAP_FAILED) {
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sprintf(errmsg, "mmap() failed on '%s'", chName);
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error(SYSTEM, errmsg);
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mmorg = NULL;
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return osiz = 0;
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}
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} else if (truncate(chName, new_siz) < 0) {
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sprintf(errmsg, "cannot truncate '%s'", chName);
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return 0;
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}
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return osiz = new_siz;
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}
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// Get data buffer
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void *
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RdataShareMap::GetMemory(size_t offs, size_t len, int fl)
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{
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if (chName && fl & RDSextend) { // resize/extend?
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if (offs + len > osiz ? !Resize(offs + len) : !Resize())
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return NULL;
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}
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if (offs + len > osiz) {
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if (chName)
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sprintf(errmsg, "requested block of %lu bytes outside map '%s'",
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(unsigned long)len, chName);
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else
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sprintf(errmsg, "requested block of %lu bytes outside %lu byte map",
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(unsigned long)len, (unsigned long)osiz);
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error(CONSISTENCY, errmsg);
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return NULL;
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}
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++bufCount;
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return (char *)mmorg + offs;
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}
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// Return data buffer
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bool
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RdataShareMap::ReleaseMemory(void *dp, int fl)
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{
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if ((dp < mmorg) | ((char *)dp >= (char *)mmorg + osiz)) {
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if (chName)
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sprintf(errmsg, "returned block outside map '%s'", chName);
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else
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sprintf(errmsg, "returned block outside %lu byte map",
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(unsigned long)osiz);
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error(CONSISTENCY, errmsg);
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return false;
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}
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bufCount -= (bufCount > 0);
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return true;
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}
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