2 \brief APC Directory Scanner
3 \details This hand-written parser/scanner traverses a directory tree and
4 tokenizes elements of the structure which correspond to APC grammar.
5 The parser is implemented as a 2D stack which populates a list of
6 child directories at each depth, handling only the leaf nodes
7 (regular files) of the directory open at the current depth to
8 conserve memory and speed up traversal.
9 The scanner works with the lexer to lexically analyze text, and
10 assumes the existence of an external 'lex' function
11 \author Jordan Lavatai
13 ----------------------------------------------------------------------------*/
15 #include <stdio.h> //print
16 #include <errno.h> //errno
18 #include <err.h> //warnx
19 #include <stdlib.h> //exit
20 #include <unistd.h> //chdir
21 #include <dirent.h> //opendir
25 #include "parser.tab.h"
27 int scanner_init(void);
28 void scanner_quit(void);
30 int scanner_scanpixels(int*,int);
33 #define DL_STACKSIZE 64
35 #ifndef DL_CD_STACKSIZE
36 #define DL_CD_STACKSIZE DL_STACKSIZE //square tree
39 int lexer_lex(const char*);
41 void lexer_pushtok(int, int);
43 int dredge_current_depth(void);
45 struct dirent
* lexer_direntpa
[], **lexer_direntpp
;
46 extern //SRC_DIR/bin/tools/apc.c
47 const char* cargs
['Z'];
51 struct dirent
* child_directory_stack
[DL_CD_STACKSIZE
],** cds
;
52 } directory_list_stack
[DL_STACKSIZE
+ 1],* dls
; //+1 for the root dir
54 /* Directory Listing Stack
55 FILO Stack for keeping an open DIR* at each directory depth for treewalk.
56 This stack is depth-safe, checking its depth during push operations, but not
57 during pop operations, to ensure the thread doesn't open too many files at
58 once (512 in c runtime), or traverse too far through symbolic links.
59 A directory listing includes a DIR* and all DIR-typed entity in the directory
60 as recognized by dirent, populated externally (and optionally).
61 This stack behaves abnormally by incrementing its PUSH operation prior to
62 evaluation, and the POP operations after evaluation. This behavior allows
63 the 'DL_CURDEPTH' operation to map to the current element in the 'dl_stack'
64 array, and it is always treated as the "current depth". This also allows us
65 to init the root directory to 'directory_list_stack'[0] and pop it in a safe
68 #define DL_STACK (directory_list_stack)
69 #define DL_STACKP (dls)
70 #define DL_CD_STACK ((*DL_STACKP).child_directory_stack)
71 #define DL_CD_STACKP ((*DL_STACKP).cds)
72 #define DL_CURDIR() ((*DL_STACKP).dirp)
73 #define DL_LEN() (DL_STACKP - DL_STACK)
74 #define DL_CD_LEN() (DL_CD_STACKP - DL_CD_STACK)
75 #define DL_INIT() (DL_STACKP = DL_STACK)
76 #define DL_CD_INIT() (DL_CD_STACKP = DL_CD_STACK)
77 #define DL_POP() ((*DL_STACKP--).dirp)
78 #define DL_CD_POP() (*--DL_CD_STACKP)
79 #define DL_PUSH(D) ((*++DL_STACKP).dirp = D)
80 #define DL_CD_PUSH(E) (*DL_CD_STACKP++ = E)
84 Initializer expects a function pointer to its lexical analysis function.
85 Sets up stack pointers and returns boolean true if 'opendir' encounters an
86 error, or if dredge_current_depth returns boolean true.
90 #define ROOTDIR (cargs['d'] ? cargs['d'] : CWDSTR)
93 DL_STACK
[0].dirp
= opendir(ROOTDIR
);
94 printf("Root dir %s\n",ROOTDIR
);
95 return !chdir(ROOTDIR
) && (DL_STACK
[0].dirp
== NULL
|| dredge_current_depth() == -1);
102 closedir(DL_CURDIR());
106 The main driver of the scanner will advance the current treewalk state and
107 tokenize tree-based push/pop operations. It will call 'lexer_lex' to
108 tokenize directory names prior to making a push operation. safe checking for
109 all returns from the filesystem handler will exit on serious system errors.
111 after pushing a new directory to the directory list, the scanner will dredge
112 the directory and alphabetically sort all file entries into the lexer's file
113 array, while placing all subdirectory entries in the current depth's child
114 directory stack to be scanned later.
116 Returns the number of tokens generated on success, -1 on error.
119 #define $($)#$ //stringifier
120 #define ERR_CHILD "Fatal: Maximum of " $(DL_CD_STACKSIZE) \
121 " child directories exceeded for directory at depth %i\n" \
123 #define ERR_DEPTH "Fatal: Maximum directory depth of " $(DL_STACKSIZE) \
124 " exceeded during directory scan\n"
125 #define ERR_DL "Fatal: Directory List Stack Corruption %x\n", DL_LEN()
127 { struct dirent
* direntp
;
131 if (DL_CD_LEN() >= DL_CD_STACKSIZE
)//fail if maxchildren exceeded
132 { fprintf(stderr
, ERR_CHILD
);
135 if (DL_CD_LEN() > 0) //There are entities to process
136 { if ((direntp
= DL_CD_POP()) == NULL
)//If the dirent is null, the library
137 goto libfail
; //function in dirent has failed
138 ntok
+= lexer_lex(direntp
->d_name
); //lex the directory name
139 if (DL_LEN() >= DL_STACKSIZE
) //fail if maxdepth exceeded
140 { fprintf(stderr
, ERR_DEPTH
);
143 if (chdir(direntp
->d_name
)) //move into the new directory
145 DL_PUSH(opendir(CWDSTR
));
146 if (DL_CURDIR() == NULL
) //open the cwd
148 lexer_pushtok(CLOPEN
, 0); //Push "Open Directory" token
150 return dredge_current_depth(); //Filter and sort the current depth
152 else if (DL_LEN() >= 0) //Any dirs left? (Including root)
153 { if (closedir(DL_POP())) //close the directory we just left
155 if (DL_LEN() == -1) //If we just popped root,
156 goto done
; //we're done
157 lexer_pushtok(CLCLOSE
, 0); //Else push "Close Directory" token,
159 if (!chdir("..")) //move up a directory and
160 goto scan
; //start over
162 fprintf(stderr
, ERR_DL
);
171 /* Directory Entity Sort and Filter (Dredge)
172 This filter removes all unhandled file types, and places any 'DT_DIR' type
173 files in the current Directory List's directory stack. Upon finishing,
174 the 'CE_STACK' is sorted alphabetically, and the current 'DL_CD_STACK' is
175 populated. Prints warnings for unhandled files.
177 Returns -1 if 'readdir' encounters an error, otherwise returns the number of
178 directory entries sent to the external 'lexer_direntpa' array.
180 typedef //so we can typecast dirent's 'alphasort()' to take const void*s
181 int (*qcomp
)(const void*, const void*);
183 int dredge_current_depth
184 #define READDIR_ERROR (-1)
185 #define READDIR_DONE (0)
186 #define DPS_LEN() (lexer_direntpp - lexer_direntpa)
187 #define DPS_PUSH(E) (*lexer_direntpp++ = E)
189 { struct dirent
** direntpp
= lexer_direntpa
;
190 DIR* cwd
= DL_CURDIR();
191 struct dirent
* direntp
;
194 if ((direntp
= readdir(cwd
)) != NULL
)
195 { switch (direntp
->d_type
)
200 if (*(direntp
->d_name
) == '.') //skip hidden files and relative dirs
205 warnx("unknown file %s: ignoring", direntp
->d_name
);
212 qsort(lexer_direntpa
, DPS_LEN(), sizeof direntp
, (qcomp
)alphasort
);
218 Scans up to 'len' pixels from the current file into 'buf'.
219 Returns the number of pixels scanned from the file, or -1 on error.
221 int scanner_scanpixels
226 //Open the current file if not yet open
228 //Verify file contents and header
229 //Read pixels into buffer