better error messages, not that anyone ever sees them

R=r
DELTA=30  (9 added, 1 deleted, 20 changed)
OCL=28104
CL=28117

diff --git a/src/lib/time/zoneinfo.go b/src/lib/time/zoneinfo.go
index 15de5a7d1f120a6d5e9014461f18334018937496..2702285c014f2f0a38635464a3ed3c200126fd00 100644 (file)
--- a/src/lib/time/zoneinfo.go
+++ b/src/lib/time/zoneinfo.go
@@ -27,10 +27,9 @@ type TimeZoneError struct {
        os.ErrorString
 }
 
-func error(bytes []byte) os.Error {
-       // TODO(rsc): provide better diagnostics
-       return TimeZoneError{ "time: malformed zoneinfo"};
-}
+var errShort = TimeZoneError{ "time: short zone file" }
+var errInvalid = TimeZoneError{ "time: invalid zone file" }
+var errLong = TimeZoneError{ "time: zone file too long" }
 
 // Simple I/O interface to binary blob of data.
 type data struct {
@@ -97,13 +96,13 @@ func parseinfo(bytes []byte) (zt []zonetime, err os.Error) {
 
        // 4-byte magic "TZif"
        if magic := d.read(4); string(magic) != "TZif" {
-               return nil, error(bytes)
+               return nil, TimeZoneError{ "time: bad zone magic" }
        }
 
        // 1-byte version, then 15 bytes of padding
        var p []byte;
        if p = d.read(16); len(p) != 16 || p[0] != 0 && p[0] != '2' {
-               return nil, error(bytes)
+               return nil, TimeZoneError { "time: bad zone file version" }
        }
        vers := p[0];
 
@@ -126,7 +125,7 @@ func parseinfo(bytes []byte) (zt []zonetime, err os.Error) {
        for i := 0; i < 6; i++ {
                nn, ok := d.big4();
                if !ok {
-                       return nil, error(bytes)
+                       return nil, errShort
                }
                n[i] = int(nn);
        }
@@ -155,7 +154,7 @@ func parseinfo(bytes []byte) (zt []zonetime, err os.Error) {
        isutc := d.read(n[NUTCLocal]);
 
        if d.error {    // ran out of data
-               return nil, error(bytes)
+               return nil, errShort
        }
 
        // If version == 2, the entire file repeats, this time using
@@ -170,16 +169,16 @@ func parseinfo(bytes []byte) (zt []zonetime, err os.Error) {
                var ok bool;
                var n uint32;
                if n, ok = zonedata.big4(); !ok {
-                       return nil, error(bytes)
+                       return nil, errShort
                }
                z[i].utcoff = int(n);
                var b byte;
                if b, ok = zonedata.byte(); !ok {
-                       return nil, error(bytes)
+                       return nil, errShort
                }
                z[i].isdst = b != 0;
                if b, ok = zonedata.byte(); !ok || int(b) >= len(abbrev) {
-                       return nil, error(bytes)
+                       return nil, errInvalid
                }
                z[i].name = byteString(abbrev[b:len(abbrev)])
        }
@@ -190,11 +189,11 @@ func parseinfo(bytes []byte) (zt []zonetime, err os.Error) {
                var ok bool;
                var n uint32;
                if n, ok = txtimes.big4(); !ok {
-                       return nil, error(bytes)
+                       return nil, errShort
                }
                zt[i].time = int32(n);
                if int(txzones[i]) >= len(z) {
-                       return nil, error(bytes)
+                       return nil, errInvalid
                }
                zt[i].zone = &z[txzones[i]];
                if i < len(isstd) {
@@ -216,7 +215,7 @@ func readfile(name string, max int) (p []byte, err os.Error) {
        n, err1 := io.FullRead(f, p);
        f.Close();
        if err1 == nil {        // too long
-               return nil, TimeZoneError{ "time: zone file too long: " + name };
+               return nil, errLong;
        }
        if err1 != io.ErrEOF {
                return nil, err1;
@@ -224,13 +223,22 @@ func readfile(name string, max int) (p []byte, err os.Error) {
        return p[0:n], nil;
 }
 
-func readinfofile(name string) (tx []zonetime, err os.Error) {
-       buf, e := readfile(name, maxFileSize);
-       if e != nil {
-               return nil, e
+func readinfofile(name string) ([]zonetime, os.Error) {
+       buf, err := readfile(name, maxFileSize);
+       if err != nil {
+               goto Error;
+       }
+       tx, err := parseinfo(buf);
+       if err != nil {
+               goto Error;
+       }
+       return tx, nil;
+
+Error:
+       if tzerr, ok := err.(TimeZoneError); ok {
+               tzerr.ErrorString += ": " + name
        }
-       tx, err = parseinfo(buf);
-       return tx, err
+       return nil, err
 }
 
 var zones []zonetime