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/* Copyright (c) 2015 Ryan Castellucci, All Rights Reserved */
#define _LARGEFILE_SOURCE
#define _LARGEFILE64_SOURCE
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include "mmapf.h"
static char *errstr[] = {
"Unknown error",
"Not a regular file",
"Incorrect file size",
""
};
char * mmapf_strerror(int errnum) {
if (errnum < MMAPF_EXFIRST) {
return strerror(errnum);
} else if (errnum < MMAPF_EXLAST) {
return errstr[errnum-MMAPF_EXFIRST];
} else {
return errstr[0];
}
}
int munmapf(mmapf_ctx *ctx) {
// TODO error checking
if (ctx->fd >= 0) {
msync(ctx->mem, ctx->file_sz, MS_SYNC);
fsync(ctx->fd);
close(ctx->fd);
}
if (ctx->mem != NULL) {
munmap(ctx->mem, ctx->mmap_sz);
}
ctx->file_sz = 0;
ctx->mmap_sz = 0;
ctx->mem = NULL;
ctx->fd = -1;
return 0;
}
int mmapf(mmapf_ctx *ctx, const unsigned char *filename, size_t size, int flags) {
size_t page_sz = sysconf(_SC_PAGESIZE);
struct stat sb;
int mmode = 0, mflags = 0, madv = 0;
int fmode = 0, fadv = 0;
int ret, fd;
// initialize
ctx->mem = NULL;
ctx->fd = -1;
ctx->file_sz = size;
// round up to the next multiple of the page size
ctx->mmap_sz = size % page_sz ? (size/page_sz+1)*page_sz : size;
mflags |= flags & MMAPF_COW ? MAP_PRIVATE : MAP_SHARED;
if (flags & MMAPF_RW) {
mmode |= PROT_READ|PROT_WRITE;
fmode |= O_RDWR;
} else if (flags & MMAPF_RD) {
mflags |= MAP_NORESERVE;
mmode |= PROT_READ;
fmode |= O_RDONLY;
} else if (flags & MMAPF_WR) {
mmode |= PROT_WRITE;
fmode |= O_WRONLY;
}
if (flags & MMAPF_CR) { fmode |= O_CREAT; }
if (flags & MMAPF_EX) { fmode |= O_EXCL; }
if (flags & MMAPF_PRE) { mflags |= MAP_POPULATE; }
if (flags & MMAPF_NOREUSE) { fadv |= POSIX_FADV_NOREUSE; }
if (flags & MMAPF_RND) { fadv |= POSIX_FADV_RANDOM; madv |= POSIX_MADV_RANDOM; }
if (flags & MMAPF_SEQ) { fadv |= POSIX_FADV_SEQUENTIAL; madv |= POSIX_MADV_SEQUENTIAL; }
if (flags & MMAPF_DONTNEED) { fadv |= POSIX_FADV_DONTNEED; madv |= POSIX_MADV_DONTNEED; }
if (flags & MMAPF_WILLNEED) {
fadv |= POSIX_FADV_WILLNEED;
// seems to fail on anonymous maps
if (filename) { madv |= POSIX_MADV_WILLNEED; }
}
if (!filename) {
ctx->mem = mmap(NULL, ctx->mmap_sz, mmode, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
} else {
if (stat(filename, &sb) == 0) { // file exists
if (!S_ISREG(sb.st_mode)) { return MMAPF_ENREG; } // not a regular file
if (sb.st_size != size) { return MMAPF_ESIZE; } // wrong size
if ((fd = open64(filename, fmode)) < 0) { return errno; } // open failed
} else if (flags & MMAPF_CR) { // file missing, but creation requested
if ((fd = open64(filename, fmode)) < 0) { return errno; } // open failed
if ((ret = posix_fallocate(fd, 0, size)) != 0) {
// EBADF is returned on an unsupported filesystem, ignore it
if (ret != EBADF) { return ret; }
}
} else { // file missing, creation *not* requested
return ENOENT;
}
//if ((ret = posix_fadvise(fd, 0, size, fadv)) != 0) { return ret; }
posix_fadvise(fd, 0, size, fadv); // ignore result
ctx->mem = mmap(NULL, ctx->mmap_sz, mmode, mflags, fd, 0);
}
if (ctx->mem == MAP_FAILED) {
return errno;
} else if (ctx->mem == NULL) {
return ENOMEM;
}
if ((ret = posix_madvise(ctx->mem, ctx->mmap_sz, madv)) != 0) {
munmap(ctx->mem, ctx->mmap_sz);
ctx->mem = NULL;
return ret;
}
#ifdef MADV_HUGEPAGE
// reduce overhead for large mappings
if (size > (1<<26)) { madvise(ctx->mem, ctx->mmap_sz, MADV_HUGEPAGE); }
#endif
#ifdef MADV_DONTDUMP
// don't include in a core dump
madvise(ctx->mem, ctx->mmap_sz, MADV_DONTDUMP);
#endif
return MMAPF_OKAY;
}