1 files changed, 167 insertions, 0 deletions
diff --git a/src/relocation.c b/src/relocation.c
new file mode 100644
index 0000000..a8157fa
--- /dev/null
+++ b/src/relocation.c
@@ -0,0 +1,167 @@
+/**
+ * @file relocation.c
+ */
+#include "relocation.h"
+#include "str.h"
+
+void replace_text(char *original, const char *target, const char *replacement) {
+    char buffer[OHMYCAL_BUFSIZ];
+    char *tmp = original;
+
+    memset(buffer, 0, sizeof(buffer));
+    while (*tmp != '\0') {
+        if (!strncmp(tmp, target, strlen(target))) {
+            size_t replen;
+            char *stop_at = strchr(tmp, '\n');
+            if (stop_at) {
+                replen = (stop_at - tmp);
+            } else {
+                replen = strlen(replacement);
+            }
+            strcat(buffer, replacement);
+            strcat(buffer, "\n");
+            tmp += replen;
+        } else {
+            strncat(buffer, tmp, 1);
+        }
+        tmp++;
+    }
+    strcpy(original, buffer);
+}
+
+void file_replace_text(const char* filename, const char* target, const char* replacement) {
+    FILE *fp = fopen(filename, "r");
+    if (fp == NULL) {
+        fprintf(stderr, "unable to open for reading: %s\n", filename);
+        return;
+    }
+
+    char buffer[OHMYCAL_BUFSIZ];
+    char tempfilename[] = "tempfileXXXXXX";
+    FILE *tfp = fopen(tempfilename, "w");
+
+    if (tfp == NULL) {
+        fprintf(stderr, "unable to open temporary fp for writing: %s\n", tempfilename);
+        fclose(fp);
+        return;
+    }
+
+    // Write modified strings to temporary file
+    while (fgets(buffer, sizeof(buffer), fp)) {
+        if (strstr(buffer, target)) {
+            replace_text(buffer, target, replacement);
+        }
+        fputs(buffer, tfp);
+    }
+
+    fclose(fp);
+    fclose(tfp);
+
+    // Replace original with modified copy
+    remove(filename);
+    rename(tempfilename, filename);
+}
+
+/**
+ * Replace all occurrences of `spattern` with `sreplacement` in `data`
+ *
+ * ~~~{.c}
+ * char *str = (char *)calloc(100, sizeof(char));
+ * strcpy(str, "This are a test.");
+ * replace_line(str, "are", "is");
+ * // str is: "This is a test."
+ * free(str);
+ * ~~~
+ *
+ * @param data string to modify
+ * @param spattern string value to replace
+ * @param sreplacement replacement string value
+ * @return success=0, error=-1
+ */
+ssize_t replace_line(char *data, const char *spattern, const char *sreplacement) {
+    if (data == NULL || spattern == NULL || sreplacement == NULL) {
+        return -1;
+    }
+
+    if (strlen(spattern) == 0 || strlen(sreplacement) == 0) {
+        return 0;
+    }
+
+    ssize_t count_replaced = 0;
+
+    char *token = NULL;
+    char buf[OHMYCAL_BUFSIZ];
+    char *bufp = buf;
+    char output[OHMYCAL_BUFSIZ];
+    memset(output, 0, sizeof(output));
+    strcpy(buf, data);
+    for (size_t i = 0; (token = strsep(&bufp, "\n")) != NULL; i++) {
+        char *match = strstr(token, spattern);
+        if (match) {
+            strncat(output, token, strlen(token) - strlen(match));
+            strcat(output, sreplacement);
+            strcat(output, "\n");
+            count_replaced++;
+        } else {
+            strcat(output, token);
+            strcat(output, "\n");
+        }
+    }
+
+    strcpy(data, output);
+    return count_replaced;
+}
+
+/**
+ * Replace all occurrences of `oldstr` in file `path` with `newstr`
+ * @param filename file to modify
+ * @param oldstr string to replace
+ * @param newstr replacement string
+ * @return success=0, failure=-1, or value of `ferror()`
+ */
+int file_replace_line(char *filename, const char *spattern, const char *sreplacement) {
+    char data[OHMYCAL_BUFSIZ];
+    char tempfile[PATH_MAX];
+    FILE *fp = NULL;
+    if ((fp = fopen(filename, "r")) == NULL) {
+        perror(filename);
+        return -1;
+    }
+
+    sprintf(tempfile, "%s.replacement", filename);
+    FILE *tfp = NULL;
+    if ((tfp = fopen(tempfile, "w+")) == NULL) {
+        fclose(fp);
+        perror(tempfile);
+        return -1;
+    }
+
+    // Zero the data buffer
+    memset(data, '\0', OHMYCAL_BUFSIZ);
+    while(fgets(data, OHMYCAL_BUFSIZ, fp) != NULL) {
+        replace_line(data, spattern, sreplacement);
+        fprintf(tfp, "%s", data);
+        memset(data, 0, sizeof(data));
+    }
+    fclose(fp);
+    fflush(tfp);
+    rewind(tfp);
+
+    // Truncate the original file
+    if ((fp = fopen(filename, "w+")) == NULL) {
+        perror(filename);
+        return -1;
+    }
+    // Zero the data buffer once more
+    memset(data, '\0', OHMYCAL_BUFSIZ);
+    // Dump the contents of the temporary file into the original file
+    while(fgets(data, OHMYCAL_BUFSIZ, tfp) != NULL) {
+        fprintf(fp, "%s", data);
+    }
+    fclose(fp);
+    fclose(tfp);
+
+    // Remove temporary file
+    unlink(tempfile);
+    return 0;
+}