我想让某个函数(save()
)获得指向结构数组的指针。dbEntry
并用数据填充它。这就是内存管理的问题了。
这是我的代码。
结构本身
typedef struct dbEntry {
unsigned int id;
char* type;
char* name;
unsigned int parent_id;
unsigned char* md5;
} dbEntry;
内存分配和调用 save()
:
int main(int argc, char const* argv[]){
if (argc != 5) arg_error();
if (strcmp(argv[1], "-s") == 0){
FILE* database = fopen(argv[2], "wb");
if (database == NULL) file_error();
dbEntry* entries = malloc(150*sizeof(dbEntry*));
for (int i=0; i<150; i++){
entries[i].id = 0;
entries[i].parent_id = 0;
entries[i].name = malloc(50*sizeof(char));
entries[i].type = malloc(10*sizeof(char));
entries[i].md5 = malloc(MD5_DIGEST_LENGTH*sizeof(unsigned char));
}
int entry_num = save(argv[4], 0, &entries);
save()
int save(char* dir_path, unsigned int parent, dbEntry** entries) {
size_t path_len = strlen(dir_path);
if (dir_path[path_len - 1] != '/') strcat(dir_path, "/");
char dp_copy[path_len];
strcpy(dp_copy, dir_path);
DIR* dir = opendir(dir_path);
struct dirent* dirent = readdir(dir);
dirent = readdir(dir);
dirent = readdir(dir);
unsigned int id = 0;
char* fpath;
if (dirent == NULL) {
fprintf(stderr,
"Directory %s doesn't exist or can't be "
"opened. Check permissions\n",
dir_path);
exit(-1);
}
while (dirent != NULL) {
entries[id]->id = id;
strcpy(entries[id]->name, dirent->d_name);
entries[id]->parent_id = parent;
if (dirent->d_type == 8) {
strcpy(entries[id]->type, "file");
size_t len = strlen(dir_path)+strlen(dirent->d_name);
fpath = malloc(len);
strcpy(fpath, dir_path);
strcat(fpath, dirent->d_name);
FILE* file = fopen(fpath, "rb");
if (file == NULL){
printf("Could not open file %s for reading\n", fpath);
exit(-1);
}
md5digest(file, entries[id]->md5);
fclose(file);
printf("Saved %s\n", strcat(dir_path, dirent->d_name));
GDB产出。
57 while (dirent != NULL) {
(gdb) n
58 entries[id]->id = id;
(gdb) n
59 strcpy(entries[id]->name, dirent->d_name);
(gdb) n
60 entries[id]->parent_id = parent;
(gdb) n
62 if (dirent->d_type == 8) {
(gdb) n
63 strcpy(entries[id]->type, "file");
(gdb) n
64 size_t len = strlen(dir_path)+strlen(dirent->d_name);
(gdb) n
65 fpath = malloc(len);
(gdb) n
66 strcpy(fpath, dir_path);
(gdb) n
67 strcat(fpath, dirent->d_name);
(gdb) p entries
$1 = (dbEntry **) 0x7ffffffee110
(gdb) p entries[0]
$2 = (dbEntry *) 0x8403490
(gdb) p entries[1]
$3 = (dbEntry *) 0x0
(gdb) p entries[2]
$4 = (dbEntry *) 0x8403260
(gdb) p entries[3]
$5 = (dbEntry *) 0xf625f4cc70b40b00
(gdb) p entries[4]
$6 = (dbEntry *) 0x7ffffffee220
(gdb) p entries[5]
$7 = (dbEntry *) 0x0
(gdb) p entries[6]
$8 = (dbEntry *) 0x8001890 <__libc_csu_init>
(gdb) p entries[7]
$9 = (dbEntry *) 0x7ffffeb51b97 <__libc_start_main+231>
(gdb) p entries[8]
$10 = (dbEntry *) 0x2000000000
(gdb) p entries[0]->name
$11 = 0x8403950 ".bash_history"
(gdb)
由于某些原因,它未能为 entries[1]
, entries[5]
和一些更多,所以程序返回 Address boundary error
当试图引用 entries[1]
.
几乎尝试了所有的方法,但问题依然存在。希望得到你的帮助。
你有 两种 问题。
随着
malloc(150*sizeof(dbEntry*))
你分配150个内存 指针 到 dbEntry
结构,而不是 dbEntry
结构本身。
我建议你从变量本身获取要分配的数据大小,如在。
dbEntry *entries = malloc(150 * sizeof *entries);
在 save
变量函数 entries
本质上是指向数组的 dbEntry
结构. 你把它当作一个指向结构的指针数组(指向数组的指针与指向数组的指针不同)。你需要去引用指针来获得原始指针,然后可以像结构体数组一样去引用它。
(*entries)[id].id = id;
或者干脆不把它作为指针传给指针。
// Note only one asterisk
// v
int save(char* dir_path, unsigned int parent, dbEntry* entries) {
...
entries[id].id = id; // Entries can be treated like a normal array of structures
...
}