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protobuf.c
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protobuf.c
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#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "simple_protobuf.h"
// read_num error when *offset < 0
static inline size_t read_num(FILE* fp, long* offset) {
size_t c, n = 0;
do {
c = fgetc(fp);
if (c < 0) {
*offset = -1;
return 0;
}
if (feof(fp)) return n;
else n |= (c & 0x7f) << (7 * (*offset)++);
} while ((c & 0x80));
return n;
}
// peek_num error when *offset < 0
static inline size_t peek_num(FILE* fp, long* offset) {
size_t c, n = 0;
do {
c = fgetc(fp);
if (c < 0) {
*offset = -1;
return 0;
}
if (feof(fp)) return n;
else n |= (c & 0x7f) << (7 * (*offset)++);
} while ((c & 0x80));
if (fseek(fp, -*offset, SEEK_CUR)) {
*offset = -2;
return 0;
}
return n;
}
// write_num returns offset
static inline long write_num(FILE* fp, size_t n) {
if (n == 0) {
if (fputc(0, fp) < 0) return -1;
return 1;
}
long i = 0;
while (n > 0) {
int ch = n & 0x7f;
if ((n >> 7) > 0) ch |= 0x80;
if (fputc(ch, fp) < 0) return -2;
n >>= 7;
i++;
}
return i;
}
simple_pb_t* get_pb(FILE* fp) {
long init_pos = ftell(fp);
if (init_pos < 0) return NULL;
long i = 0;
uint32_t struct_len = (uint32_t)read_num(fp, &i);
if (i < 0) return NULL;
if (struct_len <= 1 || struct_len >= MAX_SIMPLE_PB_STRUCT_LEN) return NULL; // 1B<struct_len<1MB
simple_pb_t* spb = malloc(struct_len + 2*sizeof(uint32_t));
if (!spb) return NULL;
spb->struct_len = struct_len;
memset(spb->target, 0, struct_len);
uint32_t offset, data_len;
for (char* p = spb->target; p < spb->target+struct_len; p += offset) {
i = 0;
offset = (uint32_t)read_num(fp, &i);
if (i < 0) return NULL;
i = 0;
data_len = (uint32_t)read_num(fp, &i);
if (i < 0) return NULL;
if (data_len == 0) continue;
if (data_len <= offset) fread(p, data_len, 1, fp);
else return NULL;
}
spb->real_len = ftell(fp) - init_pos;
return spb;
}
// get_pb_len returns 0 on error
uint32_t get_pb_len(FILE* fp) {
long i = 0;
uint32_t struct_len = (uint32_t)peek_num(fp, &i);
if (i < 0) return 0;
if (struct_len <= 1 || struct_len >= MAX_SIMPLE_PB_STRUCT_LEN) return 0; // 1B<struct_len<1MB
return struct_len + 2*sizeof(uint32_t);
}
simple_pb_t* read_pb_into(FILE* fp, simple_pb_t* spb) {
if(!spb) return NULL;
long init_pos = ftell(fp);
long i = 0;
uint32_t struct_len = (uint32_t)read_num(fp, &i);
if (i < 0) return NULL;
if (struct_len <= 1 || struct_len >= MAX_SIMPLE_PB_STRUCT_LEN) return NULL; // 1B<struct_len<1MB
spb->struct_len = struct_len;
memset(spb->target, 0, struct_len);
uint32_t offset, data_len;
for(char* p = spb->target; p < spb->target+struct_len; p += offset) {
i = 0;
offset = (uint32_t)read_num(fp, &i);
if (i < 0) return NULL;
i = 0;
data_len = (uint32_t)read_num(fp, &i);
if (i < 0) return NULL;
if (data_len == 0) continue;
if (data_len <= offset) fread(p, data_len, 1, fp);
}
spb->real_len = ftell(fp) - init_pos;
return spb;
}
long set_pb(FILE* fp, const uint32_t* items_len, uint32_t struct_len, const void* target) {
uint32_t offset = 0;
long i = 0;
char* p = (char*)target;
if (write_num(fp, struct_len) <= 0) return -1;
while (offset < struct_len) {
uint32_t data_len = items_len[i++];
if (write_num(fp, data_len) <= 0) return -2;
char* this = p + offset;
offset += data_len;
if (data_len > 1) while (data_len > 0 && !this[data_len - 1]) data_len--;
if (write_num(fp, data_len) <= 0) return -3;
if (data_len > 0) if (fwrite(this, data_len, 1, fp) <= 0) return -4;
}
return i;
}
// items_len = align_struct(uint32_t struct_size, uint32_t items_cnt, void* item_addr1, void* item_addr2...)
uint32_t* align_struct(uint32_t struct_size, uint32_t items_cnt, ...) {
va_list list;
va_start(list, items_cnt);
uint32_t* items_len = malloc(struct_size*sizeof(uint32_t));
if (items_len) {
void* this;
void* next = va_arg(list, void*);
void* end = next + struct_size;
for (uint32_t i = 0; i < items_cnt - 1; i++) {
this = next;
next = va_arg(list, void*);
items_len[i] = next - this;
}
items_len[items_cnt-1] = end - next;
}
va_end(list);
return items_len;
}
// items_len = align_struct_into(uint32_t struct_size, uint32_t* items_len, uint32_t items_cnt, void* item_addr1, void* item_addr2...)
uint32_t* align_struct_into(uint32_t struct_size, uint32_t* items_len, uint32_t items_cnt, ...) {
va_list list;
va_start(list, items_cnt);
if (items_len) {
void* this;
void* next = va_arg(list, void*);
void* end = next + struct_size;
for (uint32_t i = 0; i < items_cnt - 1; i++) {
this = next;
next = va_arg(list, void*);
items_len[i] = next - this;
}
items_len[items_cnt-1] = end - next;
}
va_end(list);
return items_len;
}