From 05f305d2679da35ddfaffa207bca738e0f7c4bd2 Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Tue, 26 Nov 2019 21:49:59 +0100
Subject: [PATCH] return stream data as HBytes
---
pdf.c | 173 +++++++++++++++++++++++++++++++++++-----------------------
1 file changed, 104 insertions(+), 69 deletions(-)
diff --git a/pdf.c b/pdf.c
index e15b5b6..4208524 100644
--- a/pdf.c
+++ b/pdf.c
@@ -17,6 +17,10 @@
#define NOT_IN(STR) h_not_in(STR, sizeof STR - 1)
+/*
+ * some helpers
+ */
+
/* a combinator to parse a given character but return a different value */
HParsedToken *
@@ -26,11 +30,27 @@ act_mapch(const HParseResult *p, void *u)
}
HParser *
-mapch(uint8_t c, uint8_t v)
+p_mapch(uint8_t c, uint8_t v)
{
return h_action(h_ch(c), act_mapch, (void *)(uintptr_t)v);
}
+/* a parser that just returns a given token */
+
+HParsedToken *
+act_return(const HParseResult *p, void *u)
+{
+ return u;
+}
+
+HParser *
+p_return__m(HAllocator *mm__, const HParsedToken *tok)
+{
+ HParser *eps = h_epsilon_p__m(mm__);
+
+ return h_action__m(mm__, eps, act_return, (void *)tok);
+}
+
/* a helper to look up a value in a dictionary */
const HParsedToken *
dictentry(const HCountedArray *dict, const char *key)
@@ -178,59 +198,9 @@ act_octal(const HParseResult *p, void *u)
#define act_xrefs h_act_last
-/*
- * validate the /Type field on a cross-reference stream.
- *
- * p = pnat nat (dict offs offs)
- */
-bool
-validate_xrstm(HParseResult *p, void *u)
-{
- const HCountedArray *tdict = H_FIELD_SEQ(2, 0);
- const HParsedToken *v = dictentry(tdict, "Type");
-
-#if 0
- if (v == NULL)
- fprintf(stderr, "stream dict has not /Type\n");
- else if (v->token_type != TT_BYTES)
- fprintf(stderr, "stream /Type is no name object\n");
- else if (v->bytes.len == 4 && strncmp("XRef", v->bytes.token, v->bytes.len) == 0)
- return true;
- return false;
-#endif
-
- return (v != NULL && v->token_type == TT_BYTES && v->bytes.len == 4 &&
- strncmp("XRef", v->bytes.token, v->bytes.len) == 0);
-}
-
-/*
- * interpret a cross-reference stream and return it in the same form as other
- * cross-reference sections:
- *
- * p = pnat nat (dict offs offs)
- * result = (xrefs dict)
- */
-HParsedToken *
-act_xrstm(const HParseResult *p, void *u)
-{
- HParsedToken *xrefs, *offs1, *offs2, *dict, *result;
-
- dict = H_INDEX_TOKEN(p->ast, 2, 0);
- offs1 = H_INDEX_TOKEN(p->ast, 2, 1);
- offs2 = H_INDEX_TOKEN(p->ast, 2, 2);
-
- // XXX decode XRefStm
-
- xrefs = H_MAKE_SEQN(2);
- xrefs->seq->elements[0] = offs1;
- xrefs->seq->elements[1] = offs2;
- xrefs->seq->used = 2;
- result = H_MAKE_SEQN(2);
- result->seq->elements[0] = xrefs;
- result->seq->elements[1] = dict;
- result->seq->used = 2;
- return result;
-}
+/* stream semantics (defined further below) */
+bool validate_xrstm(HParseResult *, void *);
+HParsedToken *act_xrstm(const HParseResult *, void *);
/*
@@ -246,10 +216,10 @@ HParser *p_xref;
HParser *kstream(HAllocator *, const HParsedToken *, void *);
void
-init_parser(void)
+init_parser(const char *input)
{
/* lines */
- H_RULE(cr, mapch('\r', '\n')); /* semantic value: \n */
+ H_RULE(cr, p_mapch('\r', '\n')); /* semantic value: \n */
H_RULE(lf, h_ch('\n')); /* semantic value: \n */
H_RULE(crlf, h_right(cr, lf)); /* semantic value: \n */
H_RULE(eol, CHX(crlf, cr, lf));
@@ -329,11 +299,11 @@ init_parser(void)
/* strings */
H_RULE(snest, h_indirect());
- H_RULE(bsn, mapch('n', 0x0a)); /* LF */
- H_RULE(bsr, mapch('r', 0x0d)); /* CR */
- H_RULE(bst, mapch('t', 0x09)); /* HT */
- H_RULE(bsb, mapch('b', 0x08)); /* BS (backspace) */
- H_RULE(bsf, mapch('f', 0x0c)); /* FF */
+ H_RULE(bsn, p_mapch('n', 0x0a)); /* LF */
+ H_RULE(bsr, p_mapch('r', 0x0d)); /* CR */
+ H_RULE(bst, p_mapch('t', 0x09)); /* HT */
+ H_RULE(bsb, p_mapch('b', 0x08)); /* BS (backspace) */
+ H_RULE(bsf, p_mapch('f', 0x0c)); /* FF */
H_RULE(escape, CHX(bsn, bsr, bst, bsb, bsf, lparen, rparen, bslash));
H_ARULE(octal, CHX(REP(odigit,3), REP(odigit,2), REP(odigit,1)));
H_RULE(wrap, IGN(eol));
@@ -359,7 +329,7 @@ init_parser(void)
/* streams */
H_RULE(stmbeg, SEQ(dict, KW("stream"), OPT(cr), lf));
H_RULE(stmend, SEQ(OPT(eol), LIT("endstream")));
- H_RULE(stream, h_left(h_bind(stmbeg, kstream, NULL), stmend));
+ H_RULE(stream, h_left(h_bind(stmbeg, kstream, (void *)input), stmend));
// XXX is whitespace allowed between the eol and "endstream"?
H_RULE(obj_, CHX(ref, null, boole, real, intg, name, string,
@@ -412,10 +382,19 @@ init_parser(void)
p_xref = xr_td;
}
+/* combine current position combined with env=(input,sz) into HBytes */
HParsedToken *
-act_return(const HParseResult *p, void *u)
+act_ks_bytes(const HParseResult *p, void *env)
{
- return u;
+ const HBytes *bs = env;
+ size_t offset = H_CAST_UINT(p->ast) / 8;
+
+ /*
+ * NB: we must allocate a new HBytes struct here because the old one is
+ * allocated only temporarily for the lifetime of the continuation
+ * below.
+ */
+ return H_MAKE_BYTES(bs->token + offset, bs->len);
}
/*
@@ -426,6 +405,7 @@ act_return(const HParseResult *p, void *u)
HParser *
kstream(HAllocator *mm__, const HParsedToken *x, void *env)
{
+ const char *input = env;
const HParsedToken *dict_t = H_INDEX_TOKEN(x, 0);
const HCountedArray *dict = H_CAST_SEQ(dict_t);
const HParsedToken *v = NULL;
@@ -439,11 +419,18 @@ kstream(HAllocator *mm__, const HParsedToken *x, void *env)
// XXX support indirect objects for the Length value!
//fprintf(stderr, "parsing stream object, length %zu.\n", sz); // XXX debug
+
+ /* dummy struct to hold the pair (input,sz) */
+ HBytes *bytes = h_alloc(mm__, sizeof(HBytes));
+ bytes->token = input;
+ bytes->len = sz;
+
HParser *tell = h_tell__m(mm__);
HParser *skip = h_skip__m(mm__, sz * 8);
- HParser *eps = h_epsilon_p__m(mm__);
- HParser *ret = h_action__m(mm__, eps, act_return, (void *)dict_t);
- return h_sequence__m(mm__, ret, tell, skip, tell, NULL);
+
+ HParser *bytes_p = h_action__m(mm__, tell, act_ks_bytes, bytes);
+ HParser *dict_p = p_return__m(mm__, dict_t);
+ return h_sequence__m(mm__, dict_p, bytes_p, skip, NULL);
fail:
#if 0
if (v == NULL)
@@ -453,10 +440,58 @@ fail:
else if (v < 0)
fprintf(stderr, "stream /Length negative\n");
#endif
- //h_pprintln(stderr, x); // XXX debug
+ //h_pprintln(stderr, p); // XXX debug
return h_nothing_p__m(mm__);
}
+/*
+ * validate the /Type field on a cross-reference stream.
+ *
+ * p = pnat nat (dict offs offs)
+ */
+bool
+validate_xrstm(HParseResult *p, void *u)
+{
+ const HCountedArray *tdict = H_FIELD_SEQ(2, 0);
+ const HParsedToken *v = dictentry(tdict, "Type");
+
+#if 0
+ if (v == NULL)
+ fprintf(stderr, "stream dict has not /Type\n");
+ else if (v->token_type != TT_BYTES)
+ fprintf(stderr, "stream /Type is no name object\n");
+ else if (v->bytes.len == 4 && strncmp("XRef", v->bytes.token, v->bytes.len) == 0)
+ return true;
+ return false;
+#endif
+
+ return (v != NULL && v->token_type == TT_BYTES && v->bytes.len == 4 &&
+ strncmp("XRef", v->bytes.token, v->bytes.len) == 0);
+}
+
+/*
+ * interpret a cross-reference stream and return it in the same form as other
+ * cross-reference sections:
+ *
+ * p = pnat nat (dict bytes)
+ * result = (xrefs dict)
+ */
+HParsedToken *
+act_xrstm(const HParseResult *p, void *u)
+{
+ HParsedToken *bytes, *dict, *result;
+
+ dict = H_INDEX_TOKEN(p->ast, 2, 0);
+ bytes = H_INDEX_TOKEN(p->ast, 2, 1);
+
+ // XXX decode XRefStm
+
+ result = H_MAKE_SEQN(2);
+ result->seq->elements[0] = bytes;
+ result->seq->elements[1] = dict;
+ result->seq->used = 2;
+ return result;
+}
/*
* main program
@@ -587,7 +622,7 @@ main(int argc, char *argv[])
err(1, "mmap");
/* build parsers */
- init_parser();
+ init_parser(input);
/* parse all cross-reference sections and trailer dictionaries */
xrefs = parse_xrefs(input, sz, &nxrefs);
--
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