Обсуждение: PQconnectdbParams returns exit value 01 (from gdb).
I'm trying to create a connection to my database with libpq. Bellow is my code:
PGconn *connect(char *file_path) {
const char **keywords;
const char **values;
char *line = malloc(LINE_SIZE);
char *prop, *val, *tmp;
int i = 0, j = 0, k = 0;
FILE *creds = fopen(file_path, "r");
if (creds == NULL) {
LOG("%s", "error: cannot open credentials file.\n");
exit(1);
}
keywords = malloc(6 * sizeof(char *));
values = malloc(6 * sizeof(char *));
while (fgets(line, LINE_SIZE, creds) != NULL) {
if (line[strlen(line) - 1] == '\n')
line[strlen(line) - 1] = '\0';
prop = line;
while(*(prop++) != '=') {
i++;
}
tmp = prop;
prop = malloc(i + 1);
strncpy(prop, line, i);
prop[i] = '\0';
keywords[j++] = prop;
val = malloc(strlen(line) - strlen(prop) + 1);
strcpy(val, tmp);
values[k++] = val;
i = 0;
}
keywords[++j] = NULL;
values[++k] = NULL;
printf("%s %s %s %s %s\n", keywords[0], keywords[1], keywords[2], keywords[3], keywords[4]); //everything is printed well here
printf("%s %s %s %s %s\n", values[0], values[1], values[2], values[3], values[4]); //here also
PGconn *conn = PQconnectdbParams(keywords, values, 1);
if (PQstatus(conn) != CONNECTION_OK) {
fprintf(stderr, "%s\n", PQerrorMessage(conn));
exit(1);
}
return conn;
}
If I run that code from main(), the printf works fine and nothing else is printed after. But trying to use that connection, I realized that in fact the PQconnectdbParams function returns value 01 (after debugging with gdb).
If I try to connect my database with the credentials from specified file, it works well.
Can anybody help me on solving that issue?
Andrei Petru Mura <mapandrei@gmail.com> writes: > I'm trying to create a connection to my database with libpq. Bellow is my > code: > keywords = malloc(6 * sizeof(char *)); > values = malloc(6 * sizeof(char *)); That looks less than safe ... what happens if you have more than five lines in the creds file? > while (fgets(line, LINE_SIZE, creds) != NULL) { > if (line[strlen(line) - 1] == '\n') > line[strlen(line) - 1] = '\0'; > prop = line; > while(*(prop++) != '=') { > i++; > } > tmp = prop; > prop = malloc(i + 1); > strncpy(prop, line, i); > prop[i] = '\0'; > keywords[j++] = prop; > val = malloc(strlen(line) - strlen(prop) + 1); > strcpy(val, tmp); > values[k++] = val; > i = 0; > } This has got a few issues, like it'll die badly if there's no '=' in a line, and not behave too well if a line overruns the fixed buffer length. > keywords[++j] = NULL; > values[++k] = NULL; But your real problem is here, where you're leaving undefined holes in the arrays. These should be j++ and k++, not ++j and ++k. If malloc doesn't give you back all-zeroes storage, PQconnectdbParams will be led to try to dereference garbage pointer values, resulting in your SIGSEGVs. regards, tom lane