strcpy : how can i not copy \n [closed] - c

Question

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 6 years ago.
Improve this question
struct configurations *read_file(char * file_name)
{
FILE *f = fopen(file_name ,"r");
if(!f)
{
printf("**********Unable to open config.txt*********");
return NULL;
}
int i, prev, count;
char *line = NULL, buff[480] = {'\0'};
size_t len;
struct configurations *config = (struct configurations *) malloc(sizeof(struct configurations));
while (getline(&line,&len,f) != -1)
{
if(!strncmp("SERVERPORT = ",line,strlen("SERVERPORT = "))){
config->server_Port = atoi(strstr(line, " = ")+3);
}
else if(!strncmp("SCHEDULING = ",line,strlen("SCHEDULING = "))){
strcpy(config->sched,strstr(line, " = ") + 3);
}

Answer 1

By subctracting 1 from the length.
There are multiple simple and obvious improvements to your code
You should always check the return value before using from strstr().
strlen("SERVERPORT = ") is a very ugly way of writing 12, inefficient too.
You should use a little bit more white spaces to make the code readable.
Don't cast the return value of malloc() it only makes it more difficult to read and might hide a bug if you forget to include stdlib.h.
ALWAYS check if malloc() returned NULL before dereferencing the pointer.
Split every line at =, remove all surrounding white spaces from the 2 resulting values and then check which variable it is and assign the corresponding value.
As it is your code will fail if SERVERPORT=1234 for example, and even if it's ugly and spaces around the = operator are better, both should be valid unless of course you explicitly want the spaces.
Also by removing surrounding white spaces you ensure that any '\n' that was read by getline() will be removed from the value.
This is a quick API a wrote just now to show you how I would do it, of course every one has their own taste and ways to do things, but I hope it helps figuring out your mistakes
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
struct KeyValue {
char *key;
char *value;
};
struct KeyFile {
size_t size;
struct KeyValue *entries;
size_t count;
};
static struct KeyFile *
keyfile_new(void)
{
struct KeyFile *kf;
kf = malloc(sizeof(*kf));
if (kf == NULL)
return NULL;
kf->entries = malloc(10 * sizeof(*kf->entries));
if (kf->entries == NULL) {
kf->size = 0;
} else {
kf->size = 10;
}
kf->count = 0;
return kf;
}
static int
keyfile_add_value(struct KeyFile *kf, const char *const key, const char *const value)
{
struct KeyValue *entry;
if (kf->count + 1 >= kf->size) {
void *pointer;
pointer = realloc(kf->entries, (kf->size + 10) * sizeof(*kf->entries));
if (pointer == NULL)
return -1;
kf->entries = pointer;
kf->size += 10;
}
entry = &kf->entries[kf->count++];
entry->key = strdup(key);
entry->value = strdup(value);
return 0;
}
static void
keyfile_free(struct KeyFile *kf)
{
for (size_t i = 0 ; i < kf->count ; ++i) {
struct KeyValue *entry;
entry = &kf->entries[i];
free(entry->key);
free(entry->value);
}
free(kf->entries);
free(kf);
}
static struct KeyFile *
keyfile_read(const char *const path)
{
FILE *file;
struct KeyFile *kf;
size_t length;
char *line;
line = NULL;
length = 0;
file = fopen(path, "r");
if (file == NULL)
return NULL;
kf = keyfile_new();
if (kf == NULL)
return NULL;
while (getline(&line, &length, file) > 0) {
char *op;
char *key;
char *value;
op = strchr(line, '=');
if (op == NULL) {
fprintf(stderr, "malformed line!\n");
} else {
*op = '\0';
key = line;
while (isspace((unsigned char) *key) != 0)
++key;
value = op + 1;
op -= 1;
while (isspace((unsigned char) *op) != 0)
*(op--) = '\0';
while (isspace((unsigned char) *value) != 0)
value += 1;
op = value + strlen(value) - 1;
while (isspace((unsigned char) *op) != 0)
*(op--) = '\0';
if (keyfile_add_value(kf, key, value) != 0)
goto error;
}
}
fclose(file);
free(line);
return kf;
error:
keyfile_free(kf);
fclose(file);
free(line);
return NULL;
}
static void
keyfile_display(const struct KeyFile *const kf)
{
for (size_t i = 0 ; i < kf->count ; ++i) {
const struct KeyValue *entry;
entry = &kf->entries[i];
fprintf(stdout, "/%s/ => /%s/\n", entry->key, entry->value);
}
}
You could improve this to add lookup functions, to find specific values in the settings file. And you can make it a standalone library to use it in many projects too.