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C语言实现mysql中存取二进制文件

时间:2007-01-04 09:48:36 来源: 作者:whsong 点击:次出处:技术无忧

关键字：C语言

最近搞mysql，这两天想用C把二进制文件（<64k，大的就存储路径了）存储到数据库里，经过我‘不懈’的搜索，发现NET上有且只有一个版本（php为例的），根本在C里行不通，我吐了一口血（之后又吐了好几次）！最后还是在mysql手册里找到了方向，是 mysql_real_escape_string给了我光明，好了，不罗嗦了，不然要有矿泉水瓶砸过来了！为了不让其它初学者吐血，我把我的code共享一下，希望大侠们指正，也欢迎鸡蛋和西红柿
#include <stdio.h>
#include <mysql/mysql.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define host "localhost" //mysql server
#define username "root"
#define password "cipher"
#define database "www"

int get_file_size(char *path, off_t *size)
{
struct stat file_stats;

if(stat(path, &file_stats))
return -1;

*size = file_stats.st_size;
return 0;
}
int main(int argc, char *argv[])
{
char *filename;
off_t *size;

MYSQL *conn;
MYSQL_RES *res_set;
MYSQL_ROW row;
MYSQL_FIELD *field;
int i, flag;
char *sql;
FILE *fp;
char *buf;
int n=0;
char *end;
unsigned long *length;

if (argc != 2) {
printf("Usage: %s srcfile/n", argv[0]);
exit(1);
}

filename = argv[1];
if ((get_file_size(filename, size)) == -1) {
perror("get file size" );
exit(1);
}

if ((buf = (char *)malloc(sizeof(char)*(*size+1))) == NULL) {
perror("malloc buf" );
exit(1);
}

if ((fp = fopen(filename, "rb" )) == NULL) {
perror("fopen file" );
exit(1);
}

if ((n = fread(buf, 1, *size, fp)) < 0) { //n=*size
perror("fread file" );
exit(1);
}

sql = (char *)malloc(sizeof(char)*n*2+256); //2n+1+strlen(other sql)
if (sql == NULL) {
perror("malloc sql" );
exit(1);
}

conn = mysql_init(NULL);
if (conn == NULL) {
printf("init mysql, %s/n", mysql_error(conn));
exit(1);
}

if ((mysql_real_connect(conn, host, username, password, database, 0, NULL, 0)) == NULL) {
printf("connect mysql, %s/n", mysql_error(conn));
exit(1);
}

strcpy(sql, "insert into www(id, name, file) values(5, 'peter', " );
end = sql;
end += strlen(sql); //point sql tail
//convert NUL(ASCII 0)、'/n'、'/r'、'/'’、'''、'"'和Control-Z and so on
*end++ = '/'';
end += mysql_real_escape_string(conn, end, buf, n);
*end++ = '/'';
*end++ = ')';

flag = mysql_real_query(conn, sql, (unsigned int)(end-sql));
if (flag != 0) {
printf("insert failed, %s/n", mysql_error(conn));
exit(1);
}

if ((mysql_real_query(conn, "SELECT file FROM www where id=5", 31)) != 0) {
printf("insert failed, %s/n", mysql_error(conn));
exit(1);
}
res_set = mysql_store_result(conn);

fclose(fp);
fp = NULL;

fp = fopen("foo.bk", "wb" );
while ((row = mysql_fetch_row(res_set)) != NULL) {
length = mysql_fetch_lengths(res_set);
for (i=0; i<mysql_num_fields(res_set); i++) {
fwrite(row[0], 1, length[0], fp);
}
}

fclose(fp);
mysql_close(conn);
free(sql);
sql = NULL;

return 0;
}
//gcc -o mysql_binary mysql_binary.c -lmysqlclient
//usage: ./mysql_binary filename
Makefile：
CXX = gcc
LIBS = -lmysqlclient
PRODUCT = mysql_binary
.LIBPATTERNS: lib%.so lib%.a
vpath % .
vpath %.c src
vpath %.h include

OBJS = mysql_binary.o
$(PRODUCT): $(OBJS)
$(CXX) $(OBJS) -o $@ $(LIBS)
.c.o:

.PHONY:clean
clean:
-rm -f $(OBJS) $(PRODUCT)

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