Annotation of libwww/Library/src/HTError.html, revision 2.19
2.1 frystyk 1: <HTML>
2: <HEAD>
3: <TITLE>Error message module for libwww</TITLE>
4: <NEXTID N="z1">
5: </HEAD>
6: <BODY>
2.18 frystyk 7:
2.9 frystyk 8: <H1>Reporting Errors and Messages to the Client</H1>
2.1 frystyk 9:
2.18 frystyk 10: <PRE>
11: /*
12: ** (c) COPYRIGHT CERN 1994.
13: ** Please first read the full copyright statement in the file COPYRIGH.
14: */
15: </PRE>
16:
2.15 frystyk 17: This module maintaines a list of error messages that might occur
18: during load of a requested URL. The error list is put out to standard
19: output by a simple function that easily can be overwritten by a smart
2.18 frystyk 20: server or client. <P>
2.15 frystyk 21:
22: <NOTE><B>Note: </B></NOTE> At the moment, <A
23: HREF="HTErrorMsg.c">HTErrorMsg()</A> is called, if the flag
24: HTRequest->error_block is set to YES, then a stream has been put up
25: or taken down in the library and therefore it is <B>VERY</B> unsafe to
2.18 frystyk 26: put anything more to the stream. <P>
27:
28: This module is implemented by <A HREF="HTError.c">HTError.c</A>, and
29: it is a part of the <A
30: HREF="http://info.cern.ch/hypertext/WWW/Library/User/Guide/Guide.html">
31: Library of Common Code</A>.
2.4 frystyk 32:
2.1 frystyk 33: <PRE>
34: #ifndef HTERROR_H
35: #define HTERROR_H
2.19 ! roeber 36: #include "sysdep.h"
2.15 frystyk 37: #include "HTAccess.h"
2.1 frystyk 38: </PRE>
39:
2.3 frystyk 40: <H2>Data Structures</H2>
2.1 frystyk 41:
2.15 frystyk 42: The basic data structure is HTErrorInfo, but in addition the following
43: types are used:
2.1 frystyk 44:
2.3 frystyk 45: <H3>Error Numbers</H3>
2.1 frystyk 46:
2.15 frystyk 47: <NOTE><B>Note: </B></NOTE> All non-HTTP error codes have index numbers
48: > HTERR_HTTP_CODES, and they will not be shown in the error-message
49: generated.
50:
2.1 frystyk 51: <PRE>
52: typedef enum _HTErrorElement {
53: HTERR_OK = 0, /* 200 */
54: HTERR_CREATED, /* 201 */
55: HTERR_ACCEPTED, /* 202 */
56: HTERR_PARTIAL, /* 203 */
57: HTERR_NO_RESPONSE, /* 204 */
58: HTERR_MOVED, /* 301 */
59: HTERR_FOUND, /* 302 */
60: HTERR_METHOD, /* 303 */
61: HTERR_NOT_MODIFIED, /* 304 */
62: HTERR_BAD_REQUEST, /* 400 */
63: HTERR_UNAUTHORIZED, /* 401 */
64: HTERR_PAYMENT_REQUIRED, /* 402 */
65: HTERR_FORBIDDEN, /* 403 */
66: HTERR_NOT_FOUND, /* 404 */
67: HTERR_INTERNAL, /* 500 */
68: HTERR_NOT_IMPLEMENTED, /* 501 */
69: HTERR_HTTP_CODES_END, /* Put all non-HTTP status codes after this */
70: HTERR_NO_REMOTE_HOST,
2.13 frystyk 71: HTERR_NO_HOST,
2.1 frystyk 72: HTERR_FTP_SERVER,
73: HTERR_FTP_NO_RESPONSE,
74: HTERR_TIME_OUT,
2.2 frystyk 75: HTERR_GOPHER_SERVER,
76: HTERR_INTERRUPTED,
2.13 frystyk 77: HTERR_CON_INTR,
2.2 frystyk 78: HTERR_CSO_SERVER,
2.16 frystyk 79: HTERR_HTTP09, /* HTTP */
2.5 frystyk 80: HTERR_BAD_REPLY, /* HTTP */
2.16 frystyk 81: HTERR_UNKNOWN_AA,
2.5 frystyk 82: HTERR_NEWS_SERVER,
2.7 frystyk 83: HTERR_FILE_TO_FTP,
2.8 frystyk 84: HTERR_MAX_REDIRECT,
2.16 frystyk 85: HTERR_EOF,
2.14 frystyk 86: HTERR_WAIS_OVERFLOW,
87: HTERR_WAIS_MODULE,
2.12 frystyk 88: HTERR_WAIS_NO_CONNECT,
2.2 frystyk 89: HTERR_SYSTEM,
2.1 frystyk 90: HTERR_ELEMENTS /* This MUST be the last element */
91: } HTErrorElement;
2.19 ! roeber 92:
! 93: #ifdef ERR_WARNING
! 94: #undef ERR_WARNING
! 95: #endif
2.3 frystyk 96:
97: typedef enum _HTErrSeverity {
98: ERR_FATAL = 0x1,
2.7 frystyk 99: ERR_NON_FATAL = 0x2,
100: ERR_WARNING = 0x4,
101: ERR_INFO = 0x8
2.3 frystyk 102: } HTErrSeverity;
103:
104: typedef struct _HTErrorInfo {
2.7 frystyk 105: int handle; /* Unique number in this stack */
2.3 frystyk 106: HTErrorElement element; /* Index number into HTErrorMsgInfo */
107: HTErrSeverity severity; /* A la VMS */
108: BOOL ignore; /* YES if msg should not go to user */
109: void * par; /* Explanation, e.g. filename */
110: unsigned int par_length; /* For copying by generic routine */
111: char * where; /* Which function */
112: } HTErrorInfo;
2.1 frystyk 113: </PRE>
114:
2.3 frystyk 115: <H2>Controling Globals</H2>
116:
2.15 frystyk 117: This variable dictates which errors should be put out when generating
118: the message to the user. The first four enumerations make it possible
119: to see `everything as bad or worse than' this level, e.g.
120: HT_ERR_SHOW_NON_FATAL shows messages of type HT_ERR_SHOW_NON_FATAL and
121: HT_ERR_SHOW_FATAL. <P>
122:
123: <B>Note:</B> The default value is made so that it only puts a message
124: to <EM>stderr</EM> if a `real' error has occurred. If a separate
125: widget is available for information and error messages then probably
126: HT_ERR_SHOW_DETAILED would be more appropriate.
2.3 frystyk 127:
128: <PRE>
129: typedef enum _HTErrorShow {
130: HT_ERR_SHOW_FATAL = 0x1,
131: HT_ERR_SHOW_NON_FATAL = 0x3,
132: HT_ERR_SHOW_WARNING = 0x7,
2.6 frystyk 133: HT_ERR_SHOW_INFO = 0xF,
134: HT_ERR_SHOW_PARS = 0x10,
135: HT_ERR_SHOW_LOCATION = 0x20,
136: HT_ERR_SHOW_IGNORE = 0x40,
137: HT_ERR_SHOW_FIRST = 0x80,
2.15 frystyk 138: HT_ERR_SHOW_LINKS = 0x100,
2.7 frystyk 139: HT_ERR_SHOW_DEFAULT = 0x13,
140: HT_ERR_SHOW_DETAILED = 0x1F,
2.10 frystyk 141: HT_ERR_SHOW_DEBUG = 0x7F
2.3 frystyk 142: } HTErrorShow;
143:
144: extern unsigned int HTErrorShowMask;
145: </PRE>
2.1 frystyk 146:
2.15 frystyk 147: This is the table containing the actual error-messages and links for
148: more information:
2.1 frystyk 149:
150: <PRE>
2.3 frystyk 151: typedef struct _HTErrorMsgInfo {
152: int code; /* Error number */
153: char * msg; /* Short explanation */
154: char * url; /* Explaning URL */
155: } HTErrorMsgInfo;
156:
157: extern HTErrorMsgInfo error_info[];
2.1 frystyk 158: </PRE>
159:
2.3 frystyk 160: <H2>Public Error Functions</H2>
161:
2.1 frystyk 162: <H3>Add an Error Message</H3>
163:
164: This function adds an error message to the error_stack list in the HTRequest
2.3 frystyk 165: structure. It always returns a negative value.
2.1 frystyk 166: <PRE>
2.3 frystyk 167: extern int HTErrorAdd PARAMS(( HTRequest * request,
2.1 frystyk 168: HTErrSeverity severity,
169: BOOL ignore,
170: int element,
171: void * par,
172: unsigned int par_length,
173: char * where));
2.2 frystyk 174: </PRE>
175:
176: <H3>Add a System Error Message</H3>
177:
2.15 frystyk 178: This function adds an error from a system call that initializes errno
179: or equivalent and adds it to the error_stack list in the HTRequest
180: structure. It always returns a negative value.
181:
2.2 frystyk 182: <PRE>
2.3 frystyk 183: extern int HTErrorSysAdd PARAMS(( HTRequest * request,
2.2 frystyk 184: HTErrSeverity severity,
185: BOOL ignore,
186: char * syscall));
2.1 frystyk 187: </PRE>
188:
189: <H3>Ignoring an Error Message</H3>
190:
2.15 frystyk 191: If an error message is not to be send to the user, e.g., output to the
192: stream, then the ignore flag must be turn on. Theese functions turns
193: it on for the latest error appended to the list or an arbitrary error
194: refered to by its handle.
195:
2.1 frystyk 196: <PRE>
2.7 frystyk 197: extern void HTErrorIgnore PARAMS((HTRequest * request, int handle));
198: extern void HTErrorIgnoreLast PARAMS((HTRequest * request));
2.1 frystyk 199: </PRE>
200:
2.15 frystyk 201: <H3>Handling Prefix for Links in Error Message</H3>
202:
203: Two functions handle the URL prefix of the links inside the error
204: message. They are quite obvious:
205:
206: <PRE>
2.17 frystyk 207: extern void HTErrorSetPrefix PARAMS((char *path));
208: extern CONST char *HTErrorGetPrefix NOPARAMS;
2.15 frystyk 209: </PRE>
210:
2.7 frystyk 211: <H3>Generating an Error Message (default to standard error)</H3>
2.3 frystyk 212:
2.8 frystyk 213: This function outputs the content of the error_stack to standard output
214: (used in Line Mode Browser), but smart clients and servers might overwrite
215: this function so that the error messages can be handled to the user in a nice
216: way. That is the reason for putting the actual implementation in HTErrorMsg.c,
217: that can be overwritten by clients and servers apart from Line Mode Browser.<P>
2.3 frystyk 218:
2.4 frystyk 219: <NOTE><B>Note: </B></NOTE>
2.1 frystyk 220:
2.8 frystyk 221: If a stream <EM>has</EM> been put up (and maybe taken down again) inside the
222: Library, then request->error_block has been set to YES. This indicates that
223: it is NOT possible any more to use the stream as output for the message.
2.1 frystyk 224: <PRE>
2.17 frystyk 225: extern void HTErrorMsg PARAMS((HTRequest * request));
2.1 frystyk 226: </PRE>
227:
228: <H3>Freeing an Error List</H3>
229:
2.8 frystyk 230: This is normally done when the HTRequest structure is freed but it might be
231: done at any other time in order to ignore a whole series of errors.
2.1 frystyk 232: <PRE>
2.17 frystyk 233: extern void HTErrorFree PARAMS((HTRequest * request));
2.1 frystyk 234: </PRE>
235:
236: <PRE>
237: #endif
238: </PRE>
239: end
240: </BODY>
241: </HTML>
242:
243:
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