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112 lines
3.2 KiB
C
112 lines
3.2 KiB
C
#include <string.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include "lib/mlr_arch.h"
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#include "input/byte_readers.h"
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#include "lib/mlr_globals.h"
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#include "lib/mlrutil.h"
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#if MLR_ARCH_MMAP_ENABLED
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static char empty_buf[1] = { 0 };
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#endif
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typedef struct _mmap_byte_reader_state_t {
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char* filename;
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int fd;
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char* sof;
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char* p;
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char* eof;
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} mmap_byte_reader_state_t;
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static int mmap_byte_reader_open_func(struct _byte_reader_t* pbr, char* prepipe, char* filename);
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static int mmap_byte_reader_read_func(struct _byte_reader_t* pbr);
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static void mmap_byte_reader_close_func(struct _byte_reader_t* pbr, char* prepipe);
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// ----------------------------------------------------------------
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byte_reader_t* mmap_byte_reader_alloc() {
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byte_reader_t* pbr = mlr_malloc_or_die(sizeof(byte_reader_t));
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pbr->pvstate = NULL;
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pbr->popen_func = mmap_byte_reader_open_func;
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pbr->pread_func = mmap_byte_reader_read_func;
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pbr->pclose_func = mmap_byte_reader_close_func;
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return pbr;
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}
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void mmap_byte_reader_free(byte_reader_t* pbr) {
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mmap_byte_reader_state_t* pstate = pbr->pvstate;
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if (pstate != NULL) {
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free(pstate->filename); // null-ok semantics
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}
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free(pbr);
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}
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// ----------------------------------------------------------------
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static int mmap_byte_reader_open_func(struct _byte_reader_t* pbr, char* prepipe, char* filename) {
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#if MLR_ARCH_MMAP_ENABLED
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// popen is a stdio construct, not an mmap construct, and it can't be supported here.
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if (prepipe != NULL) {
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fprintf(stderr, "%s: coding error detected in file %s at line %d.\n",
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MLR_GLOBALS.bargv0, __FILE__, __LINE__);
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exit(1);
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}
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mmap_byte_reader_state_t* pstate = mlr_malloc_or_die(sizeof(mmap_byte_reader_state_t));
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pstate->filename = mlr_strdup_or_die(filename);
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pstate->fd = open(filename, O_RDONLY);
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if (pstate->fd < 0) {
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perror("open");
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fprintf(stderr, "%s: Couldn't open \"%s\" for read.\n", MLR_GLOBALS.bargv0, filename);
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exit(1);
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}
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struct stat stat;
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if (fstat(pstate->fd, &stat) < 0) {
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perror("fstat");
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fprintf(stderr, "%s: could not fstat \"%s\"\n", MLR_GLOBALS.bargv0, filename);
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exit(1);
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}
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if (stat.st_size == 0) {
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// mmap doesn't allow us to map zero-length files but zero-length files do exist.
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pstate->sof = &empty_buf[0];
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} else {
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pstate->sof = mmap(NULL, (size_t)stat.st_size, PROT_READ|PROT_WRITE, MAP_FILE|MAP_PRIVATE,
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pstate->fd, (off_t)0);
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if (pstate->sof == MAP_FAILED) {
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perror("mmap");
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fprintf(stderr, "%s: could not mmap \"%s\"\n", MLR_GLOBALS.bargv0, filename);
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exit(1);
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}
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}
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pstate->eof = pstate->sof + stat.st_size;
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pstate->p = pstate->sof;
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pbr->pvstate = pstate;
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return TRUE;
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#else
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fprintf(stderr, "%s: mmap is unsupported on this architecture.\n", MLR_GLOBALS.bargv0);
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exit(1);
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return TRUE;
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#endif
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}
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static int mmap_byte_reader_read_func(struct _byte_reader_t* pbr) {
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mmap_byte_reader_state_t* pstate = pbr->pvstate;
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if (pstate->p >= pstate->eof) {
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return EOF;
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} else {
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int c = *pstate->p;
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pstate->p++;
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return c;
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}
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}
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static void mmap_byte_reader_close_func(struct _byte_reader_t* pbr, char* prepipe) {
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mmap_byte_reader_state_t* pstate = pbr->pvstate;
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if (close(pstate->fd) < 0) {
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perror("close");
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fprintf(stderr, "%s: close error on file \"%s\".\n", MLR_GLOBALS.bargv0, pstate->filename);
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exit(1);
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}
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}
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