Give more meaningful error messages.

Makefile

@@ -7,7 +7,7 @@ JSONTEST_PROG = jsontest
 HTTPTEST_OBJS = httptest.a hostname.a http.a readtcp.a seturl.a strcasecmp.a tcpconnection.a urlparser.a
 HTTPTEST_PROG = httptest
 
-DISKBROWSER_OBJS = diskbrowser.a browserevents.a browserwindow.a browserutil.a diskmount.a disksearch.a hostname.a http.a json.a jsonutil.a readtcp.a seturl.a strcasecmp.a tcpconnection.a urlparser.a asprintf.a
+DISKBROWSER_OBJS = diskbrowser.a browserevents.a browserwindow.a browserutil.a diskmount.a disksearch.a hostname.a http.a json.a jsonutil.a readtcp.a seturl.a strcasecmp.a tcpconnection.a urlparser.a netdiskerror.a asprintf.a
 DISKBROWSER_RSRC = diskbrowser.rez
 DISKBROWSER_PROG = DiskBrowser
 

browserutil.c

@@ -6,6 +6,7 @@
 #pragma noroot
 #endif
 
+#include <quickdraw.h>
 #include <window.h>
 
 #include <stdio.h>
@@ -16,14 +17,15 @@
 #include "readtcp.h"
 #include "tcpconnection.h"
 #include "json.h"
+#include "netdiskerror.h"
 
 
 void ShowErrorAlert(enum NetDiskError error, int alertNumber) {
-    char numStr[6] = "";
-    char *subs[1] = {numStr};
-    
-    snprintf(numStr, sizeof(numStr), "%u", error);
+    char *subs[1];
 
+    subs[0] = ErrorString(error);
+
+    InitCursor();
     AlertWindow(awResource+awCString+awButtonLayout,
                 (Pointer)subs, alertNumber);
 }

diskbrowser.rez

@@ -163,14 +163,18 @@ resource rPString(mountDiskButton) { "Mount Disk" };
 #define mountErrorAlert 3001
 
 resource rAlertString (searchErrorAlert) {
-    "52/"
-    "There was an error when searching for disks. (error code *0)"
+    "72/"
+    "There was an error when searching for disks.\n"
+    "\n"
+    "*0"
     "/^#0\$00"
 };
 
 resource rAlertString (mountErrorAlert) {
-    "52/"
-    "There was an error when trying to mount a disk. (error code *0)"
+    "72/"
+    "There was an error when trying to mount a disk.\n"
+    "\n"
+    "*0"
     "/^#0\$00"
 };
 

diskmount.c

@@ -133,6 +133,8 @@ static void MountFile(char *itemID, char *fileName) {
         devName.length = snprintf(devName.text, sizeof(devName.text), ".D%u", 
                                   mountURLRec.devNum);
         wantToOpenWindow = 2;
+    } else {
+        ShowErrorAlert(mountURLRec.result, mountErrorAlert);
     }
 
     free(fileURL);

netdiskerror.c

@@ -0,0 +1,57 @@
+#pragma noroot
+
+#include <stdio.h>
+#include "netdiskerror.h"
+
+static char errorBuf[20];
+
+char *ErrorString(enum NetDiskError err) {
+    switch (err) {
+    case NO_DIBS_AVAILABLE:
+        return "No more disks can be mounted via NetDisk.";
+    case OUT_OF_MEMORY:
+        return "Out of memory.";
+
+    /* SetURL errors */
+    case NAME_LOOKUP_FAILED:
+        return "The archive.org server could not be found.";
+    
+    /* StartTCPConnection and DoHTTPRequest errors */
+    case NETWORK_ERROR:
+        return "A network error was encountered.";
+    case NO_RESPONSE:
+        return "The server did not respond to a request.";
+    case INVALID_RESPONSE:
+        return "The response from the server was invalid.";
+    case EXCESSIVE_REDIRECTS:
+        return "There were too many HTTP redirects.";
+    case UNSUPPORTED_RESPONSE:
+        return "An unsupported response was received from the server.";
+    case UNSUPPORTED_HEADER_VALUE:
+        return "An unsupported header value was received from the server.";
+    case REDIRECT_ERROR:
+        return "An error was encountered when trying to redirect to the "
+               "location specified by the server.";
+    case NOT_DESIRED_CONTENT:
+        return "The server did not send the content that was expected.";
+    case DIFFERENT_LENGTH:
+        return "The length of the file on the server was different from what "
+               "was expected.";
+
+    /* File format errors */
+    case UNSUPPORTED_2IMG_FILE:
+        return "This 2mg file is not supported by NetDisk.";
+    case NOT_MULTIPLE_OF_BLOCK_SIZE:
+        return "The file is not a multiple of 512 bytes. It may not be a disk "
+               "image file, or is not in a supported format.";
+
+    /* JSON processing errors */
+    case JSON_PARSING_ERROR:
+    case NOT_EXPECTED_CONTENTS:
+        return "The response from the server was invalid. "
+               "It may not support your query.";
+   }
+    
+    snprintf(errorBuf, sizeof(errorBuf), "Error code %i.", err);
+    return errorBuf;
+}

netdiskerror.h

@@ -48,8 +48,8 @@ enum NetDiskError {
 
 
 /*
- * Return a string describing the error.  It may contain the substitution
- * string "*0", which should be replaced by the error number.
+ * Return a string describing the error.  It is only guaranteed to be valid
+ * until the next call to ErrorString().
  */
 char *ErrorString(enum NetDiskError err);