From 32fd48eab4d183042b5557ea03d06cc9ba0248d5 Mon Sep 17 00:00:00 2001
From: midipix <writeonce@midipix.org>
Date: Sun, 2 May 2021 15:43:55 +0000
Subject: heuristics: slbt_get_lconf_flags(): enhanced the string-scanning
 logic.

---
 src/internal/slibtool_lconf_impl.c | 53 ++++++++++++++++++++++++--------------
 1 file changed, 33 insertions(+), 20 deletions(-)

(limited to 'src')

diff --git a/src/internal/slibtool_lconf_impl.c b/src/internal/slibtool_lconf_impl.c
index 25d6041..9cb86a4 100644
--- a/src/internal/slibtool_lconf_impl.c
+++ b/src/internal/slibtool_lconf_impl.c
@@ -629,7 +629,6 @@ int slbt_get_lconf_flags(
 	const char *			cap;
 	uint64_t			optshared;
 	uint64_t			optstatic;
-	int				optlenmax;
 	int				optsharedlen;
 	int				optstaticlen;
 	const char *			optsharedstr;
@@ -657,10 +656,6 @@ int slbt_get_lconf_flags(
 	mark = addr;
 	cap  = &mark[st.st_size];
 
-	/* hard-coded options in the generated libtool precede the code */
-	if (st.st_size >= (optlenmax = strlen("build_libtool_libs=yes\n")))
-		cap -= optlenmax;
-
 	/* scan */
 	optshared = 0;
 	optstatic = 0;
@@ -672,43 +667,61 @@ int slbt_get_lconf_flags(
 	optstaticlen = strlen(optstaticstr);
 
 	for (; mark && mark<cap; ) {
-		if (!strncmp(mark,optsharedstr,optsharedlen)) {
+		if (!optshared && (cap - mark < optsharedlen)) {
+			mark = 0;
+
+		} else if (!optstatic && (cap - mark < optstaticlen)) {
+			mark = 0;
+
+		} else if (!optshared && !strncmp(mark,optsharedstr,optsharedlen)) {
 			mark += optsharedlen;
 
-			if ((mark[0]=='n')
+			if ((cap - mark >= 3)
+					&& (mark[0]=='n')
 					&& (mark[1]=='o')
-					&& (mark[2]=='\n'))
+					&& (mark[2]=='\n')
+					&& (mark = &mark[3]))
 				optshared = SLBT_DRIVER_DISABLE_SHARED;
 
-			if ((mark[0]=='y')
+			else if ((cap - mark >= 4)
+					&& (mark[0]=='y')
 					&& (mark[1]=='e')
 					&& (mark[2]=='s')
-					&& (mark[3]=='\n'))
+					&& (mark[3]=='\n')
+					&& (mark = &mark[4]))
 				optshared = SLBT_DRIVER_SHARED;
 
-		} else if (!strncmp(mark,optstaticstr,optstaticlen)) {
+			if (!optshared)
+				mark--;
+
+		} else if (!optstatic && !strncmp(mark,optstaticstr,optstaticlen)) {
 			mark += optstaticlen;
 
-			if ((mark[0]=='n')
+			if ((cap - mark >= 3)
+					&& (mark[0]=='n')
 					&& (mark[1]=='o')
-					&& (mark[2]=='\n'))
+					&& (mark[2]=='\n')
+					&& (mark = &mark[3]))
 				optstatic = SLBT_DRIVER_DISABLE_STATIC;
 
-			if ((mark[0]=='y')
+			else if ((cap - mark >= 4)
+					&& (mark[0]=='y')
 					&& (mark[1]=='e')
 					&& (mark[2]=='s')
-					&& (mark[3]=='\n'))
+					&& (mark[3]=='\n')
+					&& (mark = &mark[4]))
 				optstatic = SLBT_DRIVER_STATIC;
-		}
 
-		if (optshared && optstatic)
-			mark = 0;
-
-		else {
+			if (!optstatic)
+				mark--;
+		} else {
 			for (; (mark<cap) && (*mark!='\n'); )
 				mark++;
 			mark++;
 		}
+
+		if (optshared && optstatic)
+			mark = 0;
 	}
 
 	munmap(addr,st.st_size);
-- 
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