initial commit

1 files changed, 157 insertions, 0 deletions

diff --git a/config.c b/config.c
new file mode 100644
index 0000000..752dec5
--- /dev/null
+++ b/config.c
@@ -0,0 +1,157 @@
+/* Config file stuff for hcalc.
+   Copyright 2023, B. Watson.
+   Distributed under the terms of the GNU GPL.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include "hcalc.h"
+
+#define SIGNATURE "\x88\x83\xa1\xac\xa3\x82\x97\x00"
+#define SIGLEN (sizeof(SIGNATURE) - 1)
+#define TRAILER 0x626c6168L
+
+#define FILENAME ".hcalc.cfg"
+
+#define MAX_HOME 8192
+
+/* signature may end up in file(1) magic.
+   doublesize and trailer are there to avoid using configs created
+	on a different architecture.
+   Also, the file size is checked against the size of the struct.
+   In theory this could be affected by compiler options, but on my
+   system, Xlib code compiled with -fpack-struct fails to run anyway.
+   I suspect this is true everywhere...
+ */
+struct hcalc_config {
+	char signature[SIGLEN];
+	char doublesize;
+	char winsize;
+	char base;
+	char quiet;
+	double value, saved, stored;
+	long trailer;
+};
+
+char *home_dir = NULL;
+char config_path[MAX_HOME]; /* ludicrous size */
+
+size_t filesize(FILE *f) {
+	struct stat st;
+
+	if(fstat(fileno(f), &st) < 0) {
+		perror("fstat");
+		return 0;
+	}
+
+	return st.st_size;
+}
+
+void set_home_dir(void) {
+	home_dir = getenv("HOME"); /* could be fancier (getpwent()) */
+	if(!home_dir) return;
+	if(strlen(home_dir) > (MAX_HOME - 100))
+		home_dir = NULL;
+}
+
+void set_config_path(void) {
+	sprintf(config_path, "%s/%s", home_dir, FILENAME);
+/* 	fprintf(stderr, "Using config file: %s\n", config_path); */
+}
+
+void load_config(void) {
+	FILE *f;
+	struct hcalc_config conf;
+	int result;
+
+/* 	printf("load_config() called\n"); */
+	set_home_dir();
+	if(!home_dir) {
+		fprintf(stderr, "HOME not set or too long, not loading/saving config file.\n");
+		return;
+	}
+	set_config_path();
+
+	f = fopen(config_path, "rb");
+	if(!f) {
+		if(errno != ENOENT) perror(config_path);
+		return;
+	}
+
+	if(filesize(f) != sizeof(conf)) {
+		fprintf(stderr, "%s: wrong size (should be %ld bytes), ignoring.\n", config_path, sizeof(conf));
+		fclose(f);
+		return;
+	}
+
+	fread(&conf, 1, sizeof(conf), f);
+	result = ferror(f);
+	fclose(f);
+
+	if(result) {
+		perror(config_path);
+		return;
+	}
+
+	if(memcmp(conf.signature, SIGNATURE, SIGLEN) != 0) {
+		fprintf(stderr, "%s: Bad config file signature, ignoring\n", config_path);
+		return;
+	}
+
+	if(conf.doublesize != sizeof(double) || conf.trailer != TRAILER) {
+		fprintf(stderr, "%s: Bad config file architecture, ignoring\n", config_path);
+		return;
+	}
+
+/* 	fprintf(stderr, "%s: config file OK\n", config_path); */
+	value = conf.value;
+	saved = conf.saved;
+	stored = conf.stored;
+	winsize = conf.winsize;
+	base = conf.base;
+	quiet = conf.quiet;
+}
+
+void save_config(void) {
+	FILE *f;
+	struct hcalc_config conf;
+	int result;
+
+/* 	printf("save_config() called\n"); */
+	set_home_dir();
+	if(!home_dir) return;
+	set_config_path();
+
+	unlink(config_path); /* avoid symlink weirdness */
+
+	f = fopen(config_path, "wb");
+	if(!f) {
+		perror(config_path);
+		return;
+	}
+
+	memcpy(conf.signature, SIGNATURE, SIGLEN);
+	conf.doublesize = sizeof(double);
+	conf.value = value;
+	conf.saved = saved;
+	conf.stored = stored;
+	conf.winsize = winsize;
+	conf.base = base;
+	conf.quiet = quiet;
+	conf.trailer = TRAILER;
+
+	fwrite(&conf, 1, sizeof(conf), f);
+	result = ferror(f);
+
+	if(result) {
+		perror(config_path);
+	} else {
+/* 		fprintf(stderr, "Wrote config OK\n"); */
+	}
+
+	fclose(f);
+}