Annotation of libwww/Library/src/HTError.html, revision 2.11
2.1 frystyk 1: <HTML>
2: <HEAD>
3: <TITLE>Error message module for libwww</TITLE>
4: <NEXTID N="z1">
5: </HEAD>
6: <BODY>
2.9 frystyk 7: <H1>Reporting Errors and Messages to the Client</H1>
2.1 frystyk 8:
2.9 frystyk 9: This module maintaines a list of error messages that might occur during load of a requested URL. The error list is put out to standard output by a simple function that easily can be overwritten by a smart server or client. The module is
10: a part of the <A HREF="Overview.html">CERN Common WWW Library</A>.<P>
2.4 frystyk 11:
12: <NOTE><B>Note: </B></NOTE>
2.9 frystyk 13: At the moment, <A HREF="HTErrorMsg.c">HTErrorMsg()</A> is called, if the flag HTRequest->error_block is set to YES, then a stream has been put up or taken down in the library and therefore it is <B>VERY</B> unsafe to put anything more to the stream.
2.1 frystyk 14: <PRE>
15: #ifndef HTERROR_H
16: #define HTERROR_H
17: </PRE>
18:
2.3 frystyk 19: <H2>Data Structures</H2>
2.1 frystyk 20:
2.3 frystyk 21: The basic data structure is HTErrorInfo, but in addition the following types are used:
2.1 frystyk 22:
2.3 frystyk 23: <H3>Error Numbers</H3>
2.1 frystyk 24:
2.4 frystyk 25: <NOTE><B>Note: </B></NOTE>
26: All non-HTTP error codes have index numbers > HTERR_HTTP_CODES, and they will not be shown in the error-message generated.
2.1 frystyk 27: <PRE>
28: typedef enum _HTErrorElement {
29: HTERR_OK = 0, /* 200 */
30: HTERR_CREATED, /* 201 */
31: HTERR_ACCEPTED, /* 202 */
32: HTERR_PARTIAL, /* 203 */
33: HTERR_NO_RESPONSE, /* 204 */
34: HTERR_MOVED, /* 301 */
35: HTERR_FOUND, /* 302 */
36: HTERR_METHOD, /* 303 */
37: HTERR_NOT_MODIFIED, /* 304 */
38: HTERR_BAD_REQUEST, /* 400 */
39: HTERR_UNAUTHORIZED, /* 401 */
40: HTERR_PAYMENT_REQUIRED, /* 402 */
41: HTERR_FORBIDDEN, /* 403 */
42: HTERR_NOT_FOUND, /* 404 */
43: HTERR_INTERNAL, /* 500 */
44: HTERR_NOT_IMPLEMENTED, /* 501 */
45: HTERR_HTTP_CODES_END, /* Put all non-HTTP status codes after this */
46: HTERR_NO_REMOTE_HOST,
47: HTERR_FTP_SERVER,
48: HTERR_FTP_NO_RESPONSE,
49: HTERR_TIME_OUT,
2.2 frystyk 50: HTERR_GOPHER_SERVER,
51: HTERR_INTERRUPTED,
52: HTERR_CSO_SERVER,
2.5 frystyk 53: HTERR_BAD_REPLY, /* HTTP */
54: HTERR_NEWS_SERVER,
2.7 frystyk 55: HTERR_FILE_TO_FTP,
2.8 frystyk 56: HTERR_MAX_REDIRECT,
2.11 ! frystyk 57: HTERR_WAIS_SERVER,
! 58: HTERR_WAIS_NO_RESPONSE,
2.2 frystyk 59: HTERR_SYSTEM,
2.1 frystyk 60: HTERR_ELEMENTS /* This MUST be the last element */
61: } HTErrorElement;
2.3 frystyk 62:
63: typedef enum _HTErrSeverity {
64: ERR_FATAL = 0x1,
2.7 frystyk 65: ERR_NON_FATAL = 0x2,
66: ERR_WARNING = 0x4,
67: ERR_INFO = 0x8
2.3 frystyk 68: } HTErrSeverity;
69:
70: typedef struct _HTErrorInfo {
2.7 frystyk 71: int handle; /* Unique number in this stack */
2.3 frystyk 72: HTErrorElement element; /* Index number into HTErrorMsgInfo */
73: HTErrSeverity severity; /* A la VMS */
74: BOOL ignore; /* YES if msg should not go to user */
75: void * par; /* Explanation, e.g. filename */
76: unsigned int par_length; /* For copying by generic routine */
77: char * where; /* Which function */
78: } HTErrorInfo;
2.1 frystyk 79: </PRE>
80:
2.3 frystyk 81: <H2>Controling Globals</H2>
82:
2.9 frystyk 83: This variable dictates which errors should be put out when generating the
84: message to the user. The first four
2.7 frystyk 85: enumerations make it possible to see `everything as bad or worse than' this
86: level, e.g. HT_ERR_SHOW_NON_FATAL shows messages of type HT_ERR_SHOW_NON_FATAL
87: and HT_ERR_SHOW_FATAL. <P>
88:
2.9 frystyk 89: <B>Note:</B> The default value is made so that it only puts a message to
90: <EM>stderr</EM> if a `real' error has occurred. If a separate widget is available for information and error messages then probably HT_ERR_SHOW_DETAILED would
91: be more appropriate.
2.3 frystyk 92:
93: <PRE>
94: typedef enum _HTErrorShow {
95: HT_ERR_SHOW_FATAL = 0x1,
96: HT_ERR_SHOW_NON_FATAL = 0x3,
97: HT_ERR_SHOW_WARNING = 0x7,
2.6 frystyk 98: HT_ERR_SHOW_INFO = 0xF,
99: HT_ERR_SHOW_PARS = 0x10,
100: HT_ERR_SHOW_LOCATION = 0x20,
101: HT_ERR_SHOW_IGNORE = 0x40,
102: HT_ERR_SHOW_FIRST = 0x80,
2.7 frystyk 103: HT_ERR_SHOW_DEFAULT = 0x13,
104: HT_ERR_SHOW_DETAILED = 0x1F,
2.10 frystyk 105: HT_ERR_SHOW_DEBUG = 0x7F
2.3 frystyk 106: } HTErrorShow;
107:
108: extern unsigned int HTErrorShowMask;
109: </PRE>
2.1 frystyk 110:
2.3 frystyk 111: This is the table containing the actual error-messages and links for more information:
2.1 frystyk 112:
113: <PRE>
2.3 frystyk 114: typedef struct _HTErrorMsgInfo {
115: int code; /* Error number */
116: char * msg; /* Short explanation */
117: char * url; /* Explaning URL */
118: } HTErrorMsgInfo;
119:
120: extern HTErrorMsgInfo error_info[];
2.1 frystyk 121: </PRE>
122:
2.3 frystyk 123: <H2>Public Error Functions</H2>
124:
2.1 frystyk 125: <H3>Add an Error Message</H3>
126:
127: This function adds an error message to the error_stack list in the HTRequest
2.3 frystyk 128: structure. It always returns a negative value.
2.1 frystyk 129: <PRE>
2.3 frystyk 130: extern int HTErrorAdd PARAMS(( HTRequest * request,
2.1 frystyk 131: HTErrSeverity severity,
132: BOOL ignore,
133: int element,
134: void * par,
135: unsigned int par_length,
136: char * where));
2.2 frystyk 137: </PRE>
138:
139: <H3>Add a System Error Message</H3>
140:
2.3 frystyk 141: This function adds an error from a system call that initializes errno or equivalent and adds it to the error_stack list in the HTRequest structure. It always returns a negative value.
2.2 frystyk 142: <PRE>
2.3 frystyk 143: extern int HTErrorSysAdd PARAMS(( HTRequest * request,
2.2 frystyk 144: HTErrSeverity severity,
145: BOOL ignore,
146: char * syscall));
2.1 frystyk 147: </PRE>
148:
149: <H3>Ignoring an Error Message</H3>
150:
2.7 frystyk 151: If an error message is not to be send to the user, e.g., output to the stream,
152: then the ignore flag must be turn on. Theese functions turns it on for the
153: latest error appended to the list or an arbitrary error refered to by its
154: handle.
2.1 frystyk 155: <PRE>
2.7 frystyk 156: extern void HTErrorIgnore PARAMS((HTRequest * request, int handle));
157: extern void HTErrorIgnoreLast PARAMS((HTRequest * request));
2.1 frystyk 158: </PRE>
159:
2.7 frystyk 160: <H3>Generating an Error Message (default to standard error)</H3>
2.3 frystyk 161:
2.8 frystyk 162: This function outputs the content of the error_stack to standard output
163: (used in Line Mode Browser), but smart clients and servers might overwrite
164: this function so that the error messages can be handled to the user in a nice
165: way. That is the reason for putting the actual implementation in HTErrorMsg.c,
166: that can be overwritten by clients and servers apart from Line Mode Browser.<P>
2.3 frystyk 167:
2.4 frystyk 168: <NOTE><B>Note: </B></NOTE>
2.1 frystyk 169:
2.8 frystyk 170: If a stream <EM>has</EM> been put up (and maybe taken down again) inside the
171: Library, then request->error_block has been set to YES. This indicates that
172: it is NOT possible any more to use the stream as output for the message.
2.1 frystyk 173: <PRE>
174: extern void HTErrorMsg PARAMS((HTRequest * request));
175: </PRE>
176:
177: <H3>Freeing an Error List</H3>
178:
2.8 frystyk 179: This is normally done when the HTRequest structure is freed but it might be
180: done at any other time in order to ignore a whole series of errors.
2.1 frystyk 181: <PRE>
182: extern void HTErrorFree PARAMS((HTRequest * request));
183: </PRE>
184:
185: <PRE>
186: #endif
187: </PRE>
188: end
189: </BODY>
190: </HTML>
191:
192:
Webmaster
![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to HTError.html CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [Public] / libwww / Library / src