Data commit

Task/Update-a-configuration-file/C/update-a-configuration-file.c

@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define strcomp(X, Y) strcasecmp(X, Y)
+
+struct option
+{ const char *name, *value;
+  int flag; };
+
+/* TODO: dynamically obtain these */
+struct option updlist[] =
+{ { "NEEDSPEELING", NULL },
+  { "SEEDSREMOVED", "" },
+  { "NUMBEROFBANANAS", "1024" },
+  { "NUMBEROFSTRAWBERRIES", "62000" },
+  { NULL, NULL } };
+
+int output_opt(FILE *to, struct option *opt)
+{ if (opt->value == NULL)
+    return fprintf(to, "; %s\n", opt->name);
+  else if (opt->value[0] == 0)
+    return fprintf(to, "%s\n", opt->name);
+  else
+    return fprintf(to, "%s %s\n", opt->name, opt->value); }
+
+int update(FILE *from, FILE *to, struct option *updlist)
+{ char line_buf[256], opt_name[128];
+  int i;
+  for (;;)
+  { size_t len, space_span, span_to_hash;
+    if (fgets(line_buf, sizeof line_buf, from) == NULL)
+      break;
+    len = strlen(line_buf);
+    space_span = strspn(line_buf, "\t ");
+    span_to_hash = strcspn(line_buf, "#");
+    if (space_span == span_to_hash)
+      goto line_out;
+    if (space_span == len)
+      goto line_out;
+    if ((sscanf(line_buf, "; %127s", opt_name) == 1) ||
+        (sscanf(line_buf, "%127s", opt_name) == 1))
+    { int flag = 0;
+      for (i = 0; updlist[i].name; i++)
+      { if (strcomp(updlist[i].name, opt_name) == 0)
+        { if (output_opt(to, &updlist[i]) < 0)
+            return -1;
+          updlist[i].flag = 1;
+          flag = 1; } }
+      if (flag == 0)
+        goto line_out; }
+    else
+  line_out:
+      if (fprintf(to, "%s", line_buf) < 0)
+        return -1;
+    continue; }
+  { for (i = 0; updlist[i].name; i++)
+    { if (!updlist[i].flag)
+        if (output_opt(to, &updlist[i]) < 0)
+          return -1; } }
+  return feof(from) ? 0 : -1; }
+
+int main(void)
+{ if (update(stdin, stdout, updlist) < 0)
+  { fprintf(stderr, "failed\n");
+    return (EXIT_FAILURE); }
+  return 0; }