initial commit

Makefile

@@ -0,0 +1,24 @@
+CC=gcc
+CFLAGS= -c -g -Wall
+
+LDLIBS = -lcurl
+
+TARGET := isbn-lookup
+
+BUILD_DIR := ./build
+SRC_DIRS := ./src
+
+SRCS := $(shell find $(SRC_DIRS) -name '*.c')
+
+OBJS := $(SRCS:%=$(BUILD_DIR)/%.o)
+
+$(BUILD_DIR)/$(TARGET): $(OBJS)
+	$(CC) $(OBJS) -o $@ $(LDLIBS)
+
+$(BUILD_DIR)/%.c.o: %.c
+	mkdir -p $(dir $@)
+	$(CC) $(CFLAGS) -c $< -o $@
+
+.PHONY: clean
+clean:
+	rm -rf $(BUILD_DIR)

src/curl.c

@@ -0,0 +1,84 @@
+#include <curl/curl.h>
+#include <curl/easy.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "include/curl.h"
+
+#define API_URL "https://openlibrary.org/search.json?q="
+#define API_URL_LEN 38
+
+static void setup_api_link(const char* isbn, char** buf)
+{
+	size_t buffer_len;
+	
+	buffer_len = API_URL_LEN + strlen(isbn);
+	(*buf) = malloc(sizeof(char) * buffer_len);
+
+	strncpy((*buf), API_URL, API_URL_LEN + 1);
+	strncpy((*buf)+ API_URL_LEN, isbn, strlen(isbn));
+	(*buf)[buffer_len] = '\0';
+
+}
+
+#undef API_URL
+#undef API_URL_LEN
+
+static void init_get_response(get_response* buf)
+{
+	buf->len = 0;
+	buf->buf = malloc(buf->len + 1);
+	if (!(buf->buf)) {
+		perror("malloc");
+		exit(EXIT_FAILURE);
+	}
+	buf->buf[0] = '\0';
+}
+
+void free_get_response(get_response* buf)
+{
+	free(buf->buf);
+}
+
+static size_t curl_write_response(void* ptr, size_t size, size_t nmemb, get_response* buf)
+{
+	size_t new_len = buf->len + (size * nmemb);
+	buf->buf = realloc(buf->buf, new_len + 1);
+	if (!(buf->buf)) {
+		perror("realloc");
+		exit(EXIT_FAILURE);
+	}
+	memcpy(buf->buf + buf->len, ptr, size * nmemb);
+	buf->buf[new_len] = '\0';
+	buf->len = new_len;
+	return size * nmemb;
+}
+
+CURLcode book_api_call(const char* isbn, get_response* buf)
+{
+	CURL* handler;
+	CURLcode result;
+	char* request_url;
+
+	handler = curl_easy_init();
+	if (!handler) {
+		perror("curl_easy_init");
+		exit(EXIT_FAILURE);
+	}
+
+	setup_api_link(isbn, &request_url);
+	init_get_response(buf);
+
+	curl_easy_setopt(handler, CURLOPT_URL, request_url);
+	curl_easy_setopt(handler, CURLOPT_HTTPGET, 1L);
+	curl_easy_setopt(handler, CURLOPT_WRITEFUNCTION, curl_write_response);
+	curl_easy_setopt(handler, CURLOPT_WRITEDATA, buf);
+
+	result = curl_easy_perform(handler);
+
+	curl_easy_cleanup(handler);
+
+	return result;
+}
+
+

src/include/curl.h

@@ -0,0 +1,15 @@
+#include <curl/curl.h>
+
+#ifndef CURL_H
+#define CURL_H
+
+typedef struct {
+	char* buf;
+	size_t len;
+} get_response;
+
+void free_get_response(get_response* buf);
+
+CURLcode book_api_call(const char* isbn, get_response* buf);
+
+#endif

src/main.c

@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+#include "include/curl.h"
+
+int main(void)
+{
+	get_response resp;
+
+	book_api_call("9780762437818", &resp);	
+
+	puts(resp.buf);
+
+	free_get_response(&resp);
+
+	return 0;
+}