Rename most of the platform source files.

This gets rid of all those annoying 'win', 'ux' and 'gtk' prefixes
which made filenames annoying to type and to tab-complete. Also, as
with my other recent renaming sprees, I've taken the opportunity to
expand and clarify some of the names so that they're not such cryptic
abbreviations.

unix/noise.c

@@ -0,0 +1,130 @@
+/*
+ * Noise generation for PuTTY's cryptographic random number
+ * generator.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+
+#include "putty.h"
+#include "ssh.h"
+#include "storage.h"
+
+static bool read_dev_urandom(char *buf, int len)
+{
+    int fd;
+    int ngot, ret;
+
+    fd = open("/dev/urandom", O_RDONLY);
+    if (fd < 0)
+        return false;
+
+    ngot = 0;
+    while (ngot < len) {
+        ret = read(fd, buf+ngot, len-ngot);
+        if (ret < 0) {
+            close(fd);
+            return false;
+        }
+        ngot += ret;
+    }
+
+    close(fd);
+
+    return true;
+}
+
+/*
+ * This function is called once, at PuTTY startup. It will do some
+ * slightly silly things such as fetching an entire process listing
+ * and scanning /tmp, load the saved random seed from disk, and
+ * also read 32 bytes out of /dev/urandom.
+ */
+
+void noise_get_heavy(void (*func) (void *, int))
+{
+    char buf[512];
+    FILE *fp;
+    int ret;
+    bool got_dev_urandom = false;
+
+    if (read_dev_urandom(buf, 32)) {
+        got_dev_urandom = true;
+        func(buf, 32);
+    }
+
+    fp = popen("ps -axu 2>/dev/null", "r");
+    if (fp) {
+        while ( (ret = fread(buf, 1, sizeof(buf), fp)) > 0)
+            func(buf, ret);
+        pclose(fp);
+    } else if (!got_dev_urandom) {
+        fprintf(stderr, "popen: %s\n"
+                "Unable to access fallback entropy source\n", strerror(errno));
+        exit(1);
+    }
+
+    fp = popen("ls -al /tmp 2>/dev/null", "r");
+    if (fp) {
+        while ( (ret = fread(buf, 1, sizeof(buf), fp)) > 0)
+            func(buf, ret);
+        pclose(fp);
+    } else if (!got_dev_urandom) {
+        fprintf(stderr, "popen: %s\n"
+                "Unable to access fallback entropy source\n", strerror(errno));
+        exit(1);
+    }
+
+    read_random_seed(func);
+}
+
+/*
+ * This function is called on a timer, and grabs as much changeable
+ * system data as it can quickly get its hands on.
+ */
+void noise_regular(void)
+{
+    int fd;
+    int ret;
+    char buf[512];
+    struct rusage rusage;
+
+    if ((fd = open("/proc/meminfo", O_RDONLY)) >= 0) {
+        while ( (ret = read(fd, buf, sizeof(buf))) > 0)
+            random_add_noise(NOISE_SOURCE_MEMINFO, buf, ret);
+        close(fd);
+    }
+    if ((fd = open("/proc/stat", O_RDONLY)) >= 0) {
+        while ( (ret = read(fd, buf, sizeof(buf))) > 0)
+            random_add_noise(NOISE_SOURCE_STAT, buf, ret);
+        close(fd);
+    }
+    getrusage(RUSAGE_SELF, &rusage);
+    random_add_noise(NOISE_SOURCE_RUSAGE, &rusage, sizeof(rusage));
+}
+
+/*
+ * This function is called on every keypress or mouse move, and
+ * will add the current time to the noise pool. It gets the scan
+ * code or mouse position passed in, and adds that too.
+ */
+void noise_ultralight(NoiseSourceId id, unsigned long data)
+{
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    random_add_noise(NOISE_SOURCE_TIME, &tv, sizeof(tv));
+    random_add_noise(id, &data, sizeof(data));
+}
+
+uint64_t prng_reseed_time_ms(void)
+{
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return tv.tv_sec * 1000 + tv.tv_usec / 1000;
+}