Add github.c and github.h

* Implements get_github_release_notes()

1 files changed, 136 insertions, 0 deletions

diff --git a/src/github.c b/src/github.c
new file mode 100644
index 0000000..a9bbe74
--- /dev/null
+++ b/src/github.c
@@ -0,0 +1,136 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <curl/curl.h>
+#include "github.h"
+
+extern const char *VERSION;
+
+struct GHContent {
+    char *data;
+    size_t len;
+};
+
+static size_t writer(void *contents, size_t size, size_t nmemb, void *result) {
+    const size_t newlen = size * nmemb;
+    struct GHContent *content = (struct GHContent *) result;
+
+    char *ptr = realloc(content->data, content->len + newlen + 1);
+    if (!ptr) {
+        perror("realloc failed");
+        return 0;
+    }
+
+    content->data = ptr;
+    memcpy(&(content->data[content->len]), contents, newlen);
+    content->len += newlen;
+    content->data[content->len] = 0;
+
+    return newlen;
+}
+
+static char *unescape_lf(char *value) {
+    char *seq = strstr(value, "\\n");
+    while (seq != NULL) {
+        size_t cur_len = strlen(seq);
+        memmove(seq, seq + 1, strlen(seq) - 1);
+        *seq = '\n';
+        if (strlen(seq) && cur_len) {
+            seq[cur_len - 1] = 0;
+        }
+        seq = strstr(value, "\\n");
+    }
+    return value;
+}
+
+int get_github_release_notes(const char *api_token, const char *repo, const char *tag, const char *target_commitish, char **output) {
+    const char *field_body = "\"body\":\"";
+    const char *field_message = "\"message\":\"";
+    const char *endpoint_header_auth_fmt = "Authorization: Bearer %s";
+    const char *endpoint_header_api_version = "X-GitHub-Api-Version: " STASIS_GITHUB_API_VERSION;
+    const char *endpoint_post_fields_fmt = "{\"tag_name\":\"%s\", \"target_commitish\":\"%s\"}";
+    const char *endpoint_url_fmt = "https://api.github.com/repos/%s/releases/generate-notes";
+    char endpoint_header_auth[PATH_MAX] = {0};
+    char endpoint_post_fields[PATH_MAX] = {0};
+    char endpoint_url[PATH_MAX] = {0};
+    struct curl_slist *list = NULL;
+    struct GHContent content;
+
+    CURL *curl = curl_easy_init();
+    if (!curl) {
+        return -1;
+    }
+
+    // Render the header data
+    sprintf(endpoint_header_auth, endpoint_header_auth_fmt, api_token);
+    sprintf(endpoint_post_fields, endpoint_post_fields_fmt, tag, target_commitish);
+    sprintf(endpoint_url, endpoint_url_fmt, repo);
+
+    // Begin curl configuration
+    curl_easy_setopt(curl, CURLOPT_URL, endpoint_url);
+    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
+    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, endpoint_post_fields);
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writer);
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *) &content);
+
+    // Append headers to the request
+    list = curl_slist_append(list, "Accept: application/vnd.github+json");
+    list = curl_slist_append(list, endpoint_header_auth);
+    list = curl_slist_append(list, endpoint_header_api_version);
+    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list);
+
+    // Set the user-agent (github requires one)
+    char user_agent[20] = {0};
+    sprintf(user_agent, "stasis/%s", VERSION);
+    curl_easy_setopt(curl, CURLOPT_USERAGENT, user_agent);
+
+    // Execute curl request
+    memset(&content, 0, sizeof(content));
+    CURLcode res;
+    res = curl_easy_perform(curl);
+
+    // Clean up
+    curl_slist_free_all(list);
+    curl_easy_cleanup(curl);
+
+    if(res != CURLE_OK) {
+        fprintf(stderr, "curl_easy_perform() failed: %s\n",
+                curl_easy_strerror(res));
+        return -1;
+    }
+
+    // Replace all "\\n" literals with new line characters
+    char *line = unescape_lf(content.data);
+    if (line) {
+        char *data_offset = NULL;
+        if ((data_offset = strstr(line, field_body))) {
+            // Skip past the body field
+            data_offset += strlen(field_body);
+            // Remove quotation mark (and trailing comma if it exists)
+            int trim = 2;
+            char last_char = data_offset[strlen(data_offset) - trim];
+            if (last_char == ',') {
+                trim++;
+            }
+            data_offset[strlen(data_offset) - trim] = 0;
+            // Extract release notes
+            *output = strdup(data_offset);
+        } else if ((data_offset = strstr(line, field_message))) {
+            // Skip past the message field
+            data_offset += strlen(field_message);
+            *(strchr(data_offset, '"')) = 0;
+            fprintf(stderr, "GitHub API Error: '%s'\n", data_offset);
+            fprintf(stderr, "URL: %s\n", endpoint_url);
+            fprintf(stderr, "POST: %s\n", endpoint_post_fields);
+            free(content.data);
+            return -1;
+        }
+    } else {
+        fprintf(stderr, "Unknown error\n");
+        free(content.data);
+        return -1;
+    }
+
+    free(content.data);
+    return 0;
+}
\ No newline at end of file